Boss Guide: Floor 1

Overview

A guide to all bosses on the first floor in the Binding of Isaac: Rebirth. Includes attack patterns and strategies to beating them!

Introduction

In this guide we will learn about the first floor bosses of The Binding of Isaac: Rebith, strategies to effectively counter them, and their attack patterns.

Monstro

First up is Monstro. Monstro is a boss appearing in the basement and he has three basic attacks.
Floor: Basement
Abilities

• Cough: Monstro coughs a splatter of blood at the player. The shots come in different sizes and have a slight arc.
• Jump: Monstro will jump towards the player slightly. This is Monstro’s main mobility option and he cannot be hit while in mid air.
• Leap: Monstro jumps high into the air and lands on the player, creating a volley of shots when he lands, similar to his cough attack.

Strategy
Monstro can trip up newer players, but once you learn his attacks he is an easy boss. Monstro’s cough attack is directional, meaning if you stand for a moment to let him cough at you you can easily dodge in a J pattern, backing away from the shots and coming around to his side to shoot at him. When Monstro is in the air from his Leap attack, he will leave a shadow on the ground showing where he will land. Stay away from this shadow! Even if he doesn’t land on you you could still be hit by the shots created when he lands.

Gemini

Gemini. In my opinion, the easiest boss on the Basement. If you are fighting Gemini you really only need one thing; speed.
Floor: Basement
Abilities

• Chase: Gemini is almost always doing this. He moves toward the player at a fast speed, eventually stopping to pant and regain breath.
• (Little Gemini) Spit: A basic attack causing a single shot to be fired at Isaac.

Strategy
Speed will make the Gemini fight a lot easier, but even with starting speed he shouldn’t be a problem. Assuming you get a room layout with rocks in the corners just walk around the edges of the room, firing backwards at Gemini. If he stops don’t stop, keep running. If you have moved so far that he switches directions, you should switch too. Eventually the big Gemini will die leaving you with the little one. This is the only part of the fight where you have to be careful. The little Gemini loses it’s ability to spit and turns red, charging towards the player. The little Gemini suffers a huge amount of knockback from your shots, which can make killing him difficult. Apply a similar strategy as the beginning of the fight, but if you knock Gemini into your path with your shots be ready to switch directions.

Steven

Steven is a boss appearing in the Basement, but only after beating the Basement a sizable amount of times (40?). He is very similar to Gemini. However, little Steven will split from big Steven at about half health, not when the big one is killed. After separating little Steven loses the ability to shoot and charges towards the player constantly. When either is killed they release 8 tears, one in each direction.
Floor: Basement
Abilities

• Chase: Exactly the same as Gemini. Steven chases the player, eventually stopping for breath.
• (Little Steven) Spit: Little Steven spits a single tear at the player.

Strategy
Steven can be a difficult boss to face on the basement, because of the fact that the little steven separates mid fight. Employ a similar strategy to Gemini, but be weary that when killed they will fire 8 shots, one in each direction. Contrary to popular belief, which Steven you kill first has no impact whatsoever on whether you get the Little Steven item or the Steven item.

Gurdy Jr.

One of the worst bosses to fight on the first floor. Gurdy Jr. is annoying for a multitude of reasons. First of all, it has more health than any other boss that can appear on the floor. Secondly, one his attacks is almost guaranteed damage.
Floor: Cellar
Abilities

• Spawn Pooter: Gurdy Jr. Spawns a Pooter (the basic fly enemy that shoots a single shot at you).
• Shoot: Gurdy Jr. Will jump slightly then land and shoot eight tears, one in each direction.
• Charge: This is it. Gurdy Jr. charges at the player at high speeds, ricocheting off of any walls and bouncing and charging even more.

Strategy
Stay far away from Gurdy Jr, this way when it charges you have a better chance to dodge. If it spawns Pooters don’t worry too much, either Gurdy Jr. will charge them and kill them or you will kill them in the crossfire. For the basic 8-shot attack just stay back so you have a better chance at dodging.

Pin

The easiest boss in the original Binding of Isaac, Pin is no longer a pushover.
Floor: Cellar
Abilities

• Leap: Pin will leap out of the ground towards the player, then burrow into the ground when he lands. 4 shots will be fired in diagonal directions when Pin first leaps out of the ground.
• Explosive Shot: Pin pops his head out of the ground to fire an explosive shot (similar to the item Ipecac).

Strategy
Always keep moving during the Pin fight, try to flank him when in mid-air and shoot his sides. When he pops out for an explosive attack, this is your main time to deal damage to him. Fire everything you have and even feel free to get close, as the explosive shot is easy to dodge.

Widow

Widow is a boss appearing on the cellar. Hope you like spiders!
Floor: Cellar
Abilities

• Jump: Almost the same as Monstro’s basic jump attack, Widow jumps a short distance towards the player. Jumps further than Monstro but takes longer to rest between jumps.
• Spawn Spiders: Widow spawns spiders.
• Spawn Creep and Sacks: Widow spawns undamaging but slowing white creep and a Sack that spawns spiders.

Strategy
Widow is a fairly easy boss (the easiest out of the cellar bosses anyway). Keep your distance and focus on Widow. It will kill it’s own Sacks by landing on them, but you may have to kill the spiders yourself. Don’t be afraid to walk over the white liquid on the ground as it doesn’t hurt you. Do know though that it will slow you and make it easier for Widow to land on you.

Blighted Ovum

Steven wasn’t enough, so here’s a second boss similar to Gemini. The ghost starts unattatched from Blighted Ovum and will fire a Brimstone laser towards the player. The ghost is invincible.
Floor: Cellar
Abilities

• Chase: The Blighted Ovum will chase the player, getting faster as it loses health. It will leave damaging red creep behind it, so be careful. Never has to stop for breath!
• Fire: The ghost fires a Brimstone laser. This has infinite range and goes over rocks and other obstacles. Only fired when the player is to the left or right of the ghost.

Strategy
I personally find Blighted Ovum easier than Gemini or Steven because it never stops to rest. Use the same strategy as on Gemini and Steven but without worrying about stopping. Just keep running and shooting behind you, the creep will almost always dissipate before you get to it. You shouldn’t have to worry about the Brimstone laser too much.

The Haunt

The worst boss on the first floor, one of the worst in the game. Woe is the poor soul who has to fight The Haunt.
Floor: Cellar
Abilities

• ‘Spawn’ Ghosts: The Haunt and it’s ghosts are invincible, but after a few seconds one ghost will be be damagable and start attacking the player. When killed, the other two small ghosts will do the same. When these are killed the player can start attacking The Haunt. When all ghosts are killed he will go up to the top of the room and move side to side, firing Brimstone lasers at the player.

Strategy
There really is no ‘best’ anti-Haunt strategy (I wish there was!) so there’s unfortunately not a whole lot to say here. Personally I stand in either the top left or top right corner and shoot at the haunt sideways, then move downward when he charges you. Move back up when he is at a sufficient distance. Rinse and repeat.

Dingle

Dingle is one of those bosses that can trip you up easily even if you know all of his moves. He’s no Haunt, but he can still be annoying.
Floor: Basement or Cellar
Abilities

• Charge: Dingle charges towards the player three times, at the end of this attack Dingle stops moving for a few seconds to catch his breath.
• Spit: Dingle fires three tears in a basic cone (with the top of the cone being Dingle) pattern at Isaac. The tears move fast and because of this can be hard to dodge.
• Spawn Dips: Dingle will spawn 1-3 Drips (the little poop enemy)

Strategy
Dingle’s three shots just require knowing how to dodge them, after that they aren’t too much of a problem. Dingle’s charge can be easily avoided if you do one thing: stop moving for about a second then move. Dingle will charge to where you just were. Repeat this three times (I usually do this in a triangle) and you will never be hit by Dingle’s charge again.

Larry Jr.

Larry Jr. returns from the original virtually unchanged.
Floor: Basement or Cellar
Abilities

• Spawn Poop: Larry Jr. spawns poop.

Strategy
Larry Jr is a simple boss but his rapid turns can sometimes take you by surprise. Focus on his head; if you break a middle segment it will just make two Larry Jr.’s where there used to be one. There are two of him in the arena. He constantly moves around and occasionally spawns poop. Larry Jr is easier to fight in rooms with lots of rocks, as this creates designated ‘lanes’ that you know he will go down. If the room is just open you will have a tougher time. One of the Larry Jr.’s can occasionally be replaced with a Grub. Grub looks like Larry Jr. but has a darker coloring and doesn’t spawn poop. Grub will charge at Isaac when he is in his line of sight, and when killed Grub will split into many smaller worm enemies.

The Duke of Flies

The Duke of Flies is perhaps the easiest boss you can fight at this stage of the game.
Floor: Basement or Cellar
Abilities

• Spawn Big Fly: The Duke spawns a large fly that hovers towards Isaac. It can take a while to kill and though it doesn’t pose a large threat to Isaac it can act as a shield to The Duke.
• Spawn Fly: Spawns normal flies. Some will go towards Isaac, but most will orbit The Duke and protect him from Isaac’s shots.
• Puff: Occasionally the Duke of Flies will blow out air, pushing his ring of defensive flies away from him slightly

Strategy
The Duke of Flies is an easy boss. Having high damage helps to kill the large flies, but it isn’t necessary. Focus on the large flies, but other than that just try to break through the shield of flies and hurt the duke. When he dies he will explode into more flies, and all flies in the room will go towards Isaac.

Famine

Famine is one of the four Harbingers. He will always drop either a Ball of Bandages or a Cube of meat. After taking enough damage he will enter phase two and lose his phase one attacks.
Floor: Basement or Cellar
Abilities

• Charge: Famine will charge across the screen, going off on one side and appearing again on the other.
• Spawn Pooters: Famine will spawn Pooters.
• (Phase two): Shoot: Famine will shoot in a three-shot basic cone pattern like Dingle, but the shots are slower.

Strategy
Stay above or below Famine so he doesn’t charge you and will only continue to spawn Pooters. In phase two stand still to fire at Famine then side step his triple shot before stepping back into place and firing more.

Gurglings

Annoying, but not as bad as Gurdy Jr. But then again, you do have to fight two Gurglings at once…
Floor: Basement or Cellar
Abilities

• Charge: If Isaac stands left or right of the Gurglings they will charge at him, leaving damaging red creep behind them. After rushing there is a chance attack flies will be spawned.

Strategy
Gurglings are annoying (but then again, so is every enemy in the Gurdy family) because they suffer from a high amount of knockback, especially when charging. Try to stay either above or below them and fire at them as much as you can. If possible focus on one Gurgling rather than dealing even damage to both. The fight gets a lot easier when only one is left.

Fistula

Fistula. A nice, easy boss.
Floor: Cellar
Abilities

• Split: When the large Fistula is killed it will split into four smaller Fistulas. When one of these is killed it will split into two even smaller Fistulas. When one of these is killed, it turns into a Charger maggot.

Strategy
Fistula’s only attack is to wander around the room, bouncing off walls. It doesn’t actively target the player, the only way to get hit is to let yourself get hit. Fistula is an easy boss as long as you play it smart and don’t corner yourself with a bunch of tiny Fistulas and maggots.