I decided to run the game again after a whole year, and in my stream I encountered two bugs that basically destroyed the respective attempts.

This thread is dedicated for listing those issues.

• Magic Man softlock: Triggered by having Stilts active and getting hit by Magic Man's transformation spell. This will cause you to get stuck at the end of the spell, and your only option is to quit to the main menu.
• Death's box lock: Triggered by summoning Marceline when the box is up. Even after defeating the skeletons, the box will remain and Death will remain on the stage, only teleporting back when he wishes to. The box will also remain for the remainder of the fight, but the fight can be finished.
• Stalagmite hitboxes in Flame King boss arena: The spot with the stalagmites will get you stuck in them, with no way to unstuck yourself. Flame King can unstuck you, but there's no way to command him to do so (obviously).
• Button mash game freeze: Minor, but should be noted. If you press the confirm/skip button upon defeating a boss too fast, the game has a tendency to freeze.
• Tree Witch softlock: Also minor, with very low chance of encountering. This occurs when you inspect Enchiridion pages with Princess Bubblegum and Tree Witch sits on Finn. After Jake releases Finn, you will be stuck. Your only option is to quit to the main menu.