Intestinal Ire

Intestinal Ire is the first of the five bosses of Slime-San's maingame. As its name implies it is a pile of intestines trying to fight you.

You will have to fight it at the end of world 1, Excrement Fields, after beating levels 1-19, in order to continue to the following world.

Fight
You spawn on a platform left of the actual boss and your goal is to drag it down into the stomach acid.

The boss fight has three phases:

Phase 1
After spawning you just have to jump into it by morphing. Just standing on it will drag it down a bit, but be careful! It will shoot acid balls, be sure to avoid them.

Phase 2
After dragging it down a bit it will fill itself with acid, jump on one of the nearby platforms to survive. These platforms will start rotating now, just avoid the acid balls and once Intestinal Ire turns normal again, just jump on it and drag it down some more.

Phase 3
This is the final phase, almost done! Intestinal Ire is really angry now, instead of just filling itself with acid, it will try to push you into some bones, jump out of it before it hits the wall! Right after that it will move back to the middle of the room, just jump on it again and it will sooner or later fall right into the stomach acid.

Room
The boss fight happens in a closed room, the floor is stomach acid, the walls are no exit either, the ceiling is just some intestines.

There are two platforms moving up and down and later rotating or leaving the room entirely, use them to stay safe from the acid.

Right above the floor there are two more platforms with trampolines on top of them, these might help you get back to fight when falling down.