How to kill those damn bone dragons, or the importance of unit matchup and combat planning

If you don’t know how to estimate damage before the confrontation, you can get into quite a bit of trouble by overestimating your unit effectiveness or underestimating the one of an enemy unit.

So fist of all, here how damage is calculated:
Physical Damage = (damage + 10 - target armor) * (1 + resistance/weakness to physical)
Elemental Damage = (element damage + 10 - target resistance) * (1 + resistance/weakness to the element)
The result is then randomizes with 20% more or less damage as limits.

Flanking give you a bonus of 2 damage in the first hit, and as some skills can be affected by flanking, like ‘shield’ or ‘backstab’, that can be quite significant in some cases.
Guard mode increase the unit defense and resistance by 20%, or 40% if the unit has the defender skill. The increase come before skills like ‘shield’ or ‘armored’ are taken into account.

So, for example, if you take a civic guard (11 physical damage) and make him take a shot into a lost soul unit (8 armor, 60% physical resistance), it look like this:
Base Damage = (11 + 10 - 8) * (1 - 0.6) = 13 * 0.4 = 5.2
Damage Min = 5.2 * 0.8 = 4.16 → 4
Damage Max = 5.2 * 1.2 = 6.24 → 6

In case of flanking, it’s (15 * 0.4) 6 damage, then:
Damage Min = 6 * 0.8 = 4.8 → 5
Damage Max = 6 * 1.2 = 7.2 → 7
Flanking got you 16.7 to 25% more damage, for an average of around 20% more damage. Well, it’s only 1 more damage in average, but you get the idea.

It work similarly as the damage, taking into account the effect strength, defensive stats and resistances:
Physical effect success = (50 +[5 * (effect strength - target defense)]) * (1 + resistance/weakness to physical)
Element effect success = (50 +[5 * (effect strength - target resistance)]) * (1 + resistance/weakness to the element)

Resistances and weaknesses are multiple of 20.
20% is also the resistance boost that most heroes can give to their armies to certain elements.

A resistance of 20% will reduce 1 damage per 5 damage taken, so it you have a unit that has 60% of resistance to fire, then the resistance will reduce the damage by 3 per 5 damage taken.

And it’s the same for chances of getting afflicted by status effect: 55% chances of being afflicted is reduced to 44% chances if the unit has a resistance to the status effect’s element of 20%, 33 if the resistance is of 40%, and so on.

Weakness will have the opposite effect.

Now, on top of that you have a whole bunch of skills to take account of, and those define a unit strength and weaknesses.

Infantry tend to have good stat for their rank. They also have and either shield (+2 defense when not flancked) or overwhelm (+3 damage against unit with ‘shield’ and pikemens).
Basically, if an infantry has a shield, it has the shield skill. If it has a two handed weapon, it has the overwhelm skill.

Pikemens units all have initiative (unless flanked, strike first when defending), hast (+4 damage against mounted and flying unit) and phalanx (+3 defense against mounted and flying units).

Mounted archers aside, all mounted unit have charge (if this unit has moved by at least 3 tiles and hit first, +6 damage on the first strike). All mounted unit have high mobility.

Also, armored unit get +2 defense, and pierce-armor unit cancel this bonus with +2 damage. This mean armored unit have +2 defense against any non-armor-piercing unit, and that most of the time.

Here, we can already see a bit of how matchup work.
Shielded infantry with shield are harder to kill frontally with 2 bonus defense.
Overwhelming infantry are effective against both shielded infantry (especially if they flank them) and pikemens.
Pikemens can cancel charges with their initiative and get bonuses of 4 damage and 3 defense against both mounted and flying units. Don't forget that initiative don't count if they get flancked out of defense mode, though.

And there is a lot of skills. Slayers skills, devastating charge, inflict bleeding... A lot of 'em, as I said.
But don't worry, you don't need to memorise the exact effect of all of them, only to be able to understand what a unit does overall just by looking at it's description card and looking in the detail of a couple of skill if needed.
After all, there is a lot of niche skills like predation that don't matter much most of the time.

Bone dragons have 90HP, 15 armor, 12 resistance and a melee attack of 17 physical and 5 blight damage.
They have a poison breath, more on that later.
They are flying, meaning that a mere line of infantry wont stop it from going after artillery pieces and archers.
It also inflict terror to those that dare attack them in melee (more on that later) and can charge to deal extra damages. They can also eat away the casting points of your leader and heroes when damaging them, so be wary of that.
They also have immunity to poison and resistance to cold (40%), but have a weakness to fire (20%) and spirit damage (40%).

So, about the poison breath. It deal 20 blight damage, and that is significant, especially against low-tier units. It’s power is roughly as powerful as a melee strike, as most unit has lower resistance than defense, so if it hit 3 or more target, it’s as if it got 3 hits free of retaliation.
To reduce it’s effect, you’ll have to got into a formation to prepare for it.

Separate your stack in 3 pairs. Each pair must be far enough to avoid the dragon hitting 2 pairs at the same time, and for each pair the one at the back must be a few tiles away from the one at the front as to force the dragon to advance as much as possible and show his... bonny back.
Don’t forget to put your unit out of range for a dragon charge but close enough for your melee units to be able to flank it once the dragon advance.
This way, only 2 unit will get hit by the poison breath, and you’ll get to flank the dragon so as to avoid the dangerously powerful retaliation of the dragon.
If you have hard time imagining the area of effect, you can click on the dragon then on it’s breath attack icon to look at the area of effect it has.

But dragons also have the terror effect, and that’s one hell of status effect. Each time a unit attack it in melee, it must resist the terror effect or they’ll get terrorized, making them running away from the field as fast as possible for the next 2 turns, even if it mean that they’ll get hit by an opportunity attack and killed on the spot.
The power of terror is 9 and it’s a spiritual effect. This mean that a unit with 9 resistance have 50% chances to get terrorized, and knowing that it happen each time you strike the dragon in melee, it’s very a powerful effect.
There are a few ways to counter terror, or at least increase chances to resist it, with heroes, like Blood Brothers (warlord level 7 skill), Touch of Faith (theocrat level 3 skill) or Nature Resistance (arch-druid level 1 skill). Some support units similarly have abilities that can help, like the healing skill from human priest, and some empire upgrades and spells can also help to deal with it.

So, now we know about the dragon, about terror and how to reduce it’s breath attack effect, what about the unit we’ll use?
We’ll consider second level of governance at best, and look at an example.

First, all draconian have resistance to fire and weakness to cold. It’s irrelevant in this matchup, but bone dragon can be followed by unit inflicting cold damage (lost souls, archont priestress…), so don’t forget about that when fighting it.
So, lets now take the tools draconian has at their disposal to deal with this threat.

- - - Draconian hatchling
The fire damage isn’t strong enough to have value, considering the high resistance stat from the bone dragon, and there isn’t any other argument for this irregular unit.

- - - Draconian crusher
The draconian’s infantry is also out. Their HP won’t make it with the low defense and resistance, they don’t have any useful bonus against dragons, and their damage isn’t enough as it is. They can be useful against archont infantry and archers, though, thanks to overwhelm and projectile resistance.

- - - Draconian flamer
I love using flamers, but this really isn’t the place to use them.
Their ranged attack deal physical and fire damage, so it’s weaker against unit that have both defense and resistance above 10. Against bone dragon, they’ll deal around 7 damage per shot.
Their strength is in their splash damage and in attacking units with low defense and resistance. You’ll get much more value targeting multiple/weaker units like lost souls, banshee and so on.

- - - Draconian charger
Draconnian chargers has 46 HP, 9 defense, 8 resistance and an attack of 11.
They are quite squishy for pikemen with their low defense and no armor, but compensate with minor flying, more movement points and charge.
Against the bone dragon, it will have a base of 15 damage and 12 defense, since dragons are flying units. It also won’t get charged unless flanked, and it can easily flank the dragon while getting a charge bonus, making a possible +8 bonus damage on the first strike.

Normally, draconian’s pikemen will take around 22 damage from the breath and around 22 damages from melee attack. In defense, the breath inflict them around 20 damage and the melee attack 18 poison damage, but most importantly, they can't get flancked in defense.
They have 45% chances of resisting terror, 55% if in defense.
As for damage, they inflict around 10 damage per hit when attacking frontally, but the real deal is when they hit the dragon by flanking with a charge, inflicting then around 18 damage.
All of that mean that they can survive around 2 or 3 hit before dying, and if you use them well, they can inflict 14 to 34 damage to the dragon without dying on the first turn of melee.
If you took the second military governance, they also recover some HP each turn, so they may survive 3 hit when they wound normaly only survive to 2.

- - - Draconian elder
Draconian’s support unit has 36HP, 9 defense and 11 resistance. In short, they can be one shot by bone dragon if they flank them in a charge.
However, they have a repetitive 8 fire damage ranged attack, and that can be decisive: if you get one of there close with all their action points, you can inflict aroung 21 damage (23% of the bone dragon HP) without taking any in return.

On top of that, they have an ability to add 5 fire damage to an ally’s attack and high moral, and against undead, bone dragon included, this can be quite useful.
If you use it on a draconian charger (for example), you add around 4 damage per hit once the bone dragon resistance and fire weakness are taken into account. It also increase the chances of inflicting a critical hit or decrease the risk for a fumble to happen, depending on the unit current moral.

With silver rank they get inflict immolation, giving him 42% chances to inflict immolation to the bone dragon for 3 turns, inflicting a penalty of 1 defense & resistance and 2 melee strength accompanied by 3 fire damage per turn. There is also a moral penalty, but remember that bone dragon, as undead, are immune to most moral penalty and bonuses.

- - - Draconian Raptor
As a general rule, if the target have more than 11 defense and resistance, a few exception aside, you’ll only get demerit from dividing your damage into physical damage and elemental, and the draconian raptor vs bone dragon is the perfect example of that.

Draconian raptor have 55HP, 11 defense and 9 resistance. They can take a bit more beating than the pikemen, both from the bone dragons or from other unit, and have easier time resisting terror (5% more chances to resist).
They have high mobility, charge, and an attack dealing 6 physical and 6 fire damage.

So, bone dragon have a 20% weakness to fire, so having fire damage is better, right? Well… No.
While the fire damage look like a good thing against bone dragon, these have 15 defense and 12 resistance, so you end up with only (6+10-15) 1 physical damage and (6+10-12) 4 fire damage, 5 after taking fire weakness into account. At 6 damage per hit on average, 12 in case of a charge, they actually inflict less damage than if they had 12 physical damage like human cavalry does (12+10-15 = 7).

In general, send your raptor against archont archers and infantry, lost souls, banshee and so on, you’ll get a lot more value attacking these with them.

However, there is one way to make them effective against bone dragon, and that’s by reinforcing them with the draconian support unit skill, making their fire damage go from 6 to 11. If you calculate the damage (11+10-12=9) then take into account the fire weakness, they now inflict 1 physical and 11 fire damage per hit (so 12 damage), and 9 physical and 11 fire damage (so 20) in case of a charge by flanking.
They still hit weaker than a pikemen reinforced by that same ability (13 damage or 21 by charging and flanking), but it can be advantageous to have a unit that can take one more hit from the start… or if you have a raptor in your army either way.

Just like draconian elders at silver, they get inflict immolation at gold rank.

- - - Draconian flyer
With 64 HP, 11 defense and 11 resistance, the draconian flyer can take some beating from a bone dragon. It is, however, not their specialty, nor the optimal way to use it.
With 16 physical damage, high mobility, projectile resistance and overwhelm, they are best used to rapidly kill support unit, archers and shielded infantry, and you can find all of those in ossuary armies. You also need to take those out, else it wont matter if you take out the bone dragon or not as the rest of your army will get smashed by those.

In general, you can sum up countering bone dragon with low tier units as using pikemen, with their bonus to damage and defense, and support unit, though only if they deal elemental damage other than poison and cold. But, of course, those are not the only options you have in hand.

Some class unit, either in general or with specific racial combination, can be really interesting, even in early game.
For example, monster hunters has dragon slayer (+3 damage vs dragons) and get undead slayer at bronze rang (+3 damage against undead), so a +3 to +6 bonus against them.
Human monster hunters, that are as average as possible among them in term of stat, have 50HP, 12 defense and 10 resistance, a melee attack of 12 and a ranged attack of 11 damage, and on top of that they are fast for footman. They also all have armor, even if draconian or goblins.
In short, they are better in every ways than a lot of pikemen against bone dragon (though not against cavalry).
The draconian one specifically has a ranged attack dealing 11 fire damage, so they also get bonus damage against bone dragons with it.

Some racial governance bonus can also make some unit surprisingly effective against bone dragon, like humans with the 1st military governance giving civic guard ‘throw net’ or the tigrans with the 2nd military governance giving that same ability to prawlers.
If it work, you have 2 turns where you can destroy it without retaliation. If not, well they reduced it’s actions points without side effect outside from your unit actions being used. If you got 2, you can reduce theirs action points to 0 even if the dragon resist to both tries, so you can still beat the crap out of it.

Finally, some spells and effects can cripple to some extent the bone dragon effectiveness, and not just among high level spells.
For example, Skin of Oil spell from fire adept can make it weaker and more vulnerable, especially against draconian, by inflicting -2 melee damage, -2 defense and resistance, plus a 60% fire weakness.
With that, a draconian raptor suddenly inflict 10 damage on bone dragons, 18 if they make a flanking charge, and using the draconian elder boost on them make it 15 damage per hit or 23 in flanking charge. Devastating.

The Rot spell from water adept inflict 20 physical damage to up to 5 machine/undead unit while weakening them for 5 turns, inflicting -1 defense and resistance, -200 moral and 60% blight weakness.
The spell will barely do any damage (around 5 or 6, I forgot if the resistance reduction happen before or after the damage), but it can be quite powerful with orcs (support unit with a tri-elemental fire/spirit/blight damage, also curse is a powerful blight status effect) or as a rogue (loads of poison damage).

The Cardinal Culling spell from Grey Guard master inflict a 40% weakness to physical damage while inflicting a -5 penalty to melee damage to all hostiles unit from the same type.
This one is best used when there are 2 bone dragon (or more), though even if there is only one, you can easily make it worthwhile with any races or classes, especially since Essence Harvest will recover at least some of the casting points each time you kill an undead.

There are a lot of combination with races, classes and specialization to make bone dragons relatively easy to kill, or at least not as dangerous as before.

When you look at a unit description, there are a few indicator that can help you to find how to use them and how to counter them.
They have shield? Flanking them will inflict 4 more damage in the first hit than taking them frontally. Don’t hesitate to put it on guard to avoid being flanked if there are cavalry/flying unit among your opponent.
This is a flying unit (not floating, flying)? Pikemen have 3 more defense and inflict 4 more damage against those. Use them to get support and ranged unit, or to get behind a shielded unit that isn’t on guard.
This is a pikemen unit? Two-handed infantry, bears and a few over get bonus against it. Avoid attacking unless you get a real advantage of doing so, since they get the first hit with initiative and they are weaker than infantry.
This is a cavalry unit? They are mobile but vulnerable to pikemen units. Avoid those and try to flank the enemy while getting a charge when the opportunity present itself. Unless they are mounted archers, those are the ultimate skirmishers.
And so on.

Some unit can also be used in very specific ways.

The musketeer, for instance, can be used in three ways when shooting.
You can shot from afar a dangerous target, hopping to slow it down, or you can wait for the enemy to get close then shot them at close range from behind some kind of infantry, or you can even go for a close-ranged flanking attack, inflicting serious damage to the target and turning them in the musketeer direction.
No matter the way you use them, you can then use them in melee as long as the enemy isn’t a high tier unit, as they are decent enough to do so.
After all, they have 45HP, 11 defense + armor, and 9 resistance coupled with 10 melee attack, making them one of the strongest ‘archer’ in melee with mounted archers and orc razorbows. And with a ranged attack inflicting 25 damage, and possibly taking away an action point from the target, but with the need to reload to take a second shot, you can definitively see where those ideas come from.

Take a good look at the units and spells you have at disposal, and at what the opponent has. Think both in strategical and tactical level in a way to create your own play-style. This way, you can get an edge in any combat.

I hope this guide was useful to those who have a hard time getting in this game and those who wanted to help other peoples to get into this game.
Thank you for keeping with me, and thank you in advance for any constructive criticism.