Overview
Here is a list of all attacks that Sans, the final boss in UNDERTALE, preforms during his battle. Yes, they are in order, and will be in this EXACT ORDER unless you eat a healing item. Otherwise, they are in order.
First Wave
This is the first wave of (13) attacks Sans will do. Key: ~ = middle, < = left, > = right, ^ = up, and v = down.
1. “Strongest Attack” Down throw, Maneuver through wavy bone path, Gaster Blaster Pattern: (~, ^, ~, ^).
2. Jump through slots (all low down)
3. Blue – White jumps (blue = stay still and white = jump over)
4. Jump through slots (assorted heights; always random)
5. First Platforms (3rd platform has bones above; bone comes in at very end)
6. Second platforms ( pretty straightforward; last platform: jump above tall bone and stay still)
7. Left and Right bone platforms – stay at bottom, move left, jump up, right, and repeat.
8. 3 Pillar slots (hard – slide through medium sized slots)
9. Gaster Blaster Platforms (ALWAYS RANDOM – Very hard)
10. 3 Pillar slots (very hard – slide through small sized slots)
11. Jump through slots (all low; faster)
12. Slot-to-slot (stay in one, jump up, left and repeat until done)
13. Jump through slots (assorted heights; random; faster)
Sans should now tell you that you can still be a good person and allow you to spare, but DO NOT SPARE! You will be instantly killed!
Second Wave
These attacks take place after Sans says, “welp, it was worth a shot”.
(list resumes after 13.)
14. On-and-off – His attacks will change abruptly after a few seconds and will change about 4-5 times. (always random)
*A bone should be on the left side of menu – CAN DEAL DAMAGE WHILE SELECTING SANS’ NAME – BE CAREFUL*
You should be changed to a red heart now.
15. Gaster Blaster Flurry – rapidly firing gaster blasters will fire acros the board – Sea Tea recommended
16.On-and-off – abruptly changing attacks (includes wavy bone path; harder this time)
*Sans should now be putting bones across the FIGHT/ACT/ITEM/MERCY buttons; you can take damage white trying to eat healing items*
17. Slamming – He will slam you around the box; jump shortly after getting hit against the wall to avoid bones.
Pattern: (<, >, ^, v, >, ^, >, v, ^)
18. Slamming
Pattern: (>, <, >, >, ^, ^, v, >, <)
19. Gaster Blaster Flurry (Harder; wider beams; Sea Tea recommended)
20. Bones on either side of screen will go up (right) Down (left); MOVE IN COUNTERCLOCKWISE CIRCLES TO AVOID!
21. On-and-off – EXTREME! (3x+ Wavy path)
22. Slamming (bones are taller this time)
23. Slamming
Pattern: (>, v, v, <), then you will be taken straight to attack 20’s pattern.
Straitht to EXTREMELY FAST WAVY PATH, then move up and down to avoid pillars. Next, move straight to the middle to avoid a narrowing path, and last avoid the slam on the far wall.
24. On-and-off ; EXTREMELY HARD!
Pattern: (top, bottom, right, and left indicate places bones come from) (top and bottom, top and left, bottom and right, left)
Third Wave
This is the final wave consisting of 2 attacks.
25. Gaster Blaster Spiral – HARDEST ATTACK! – Move counter-clockwise in a paced manner, avoiding the center for about 10 seconds. THIS IS THE FINAL ATTACK!
26. Sans will slam you randomly against the walls. You cannot die. You will end with 1 health.
Congratulations, you are done! Wait for him to fall asleep and move the box over the FIGHT icon to attack him and thus end the battle.
THANK YOU for reading this guide. took long enough to write.