This page of the Psychonauts 2 guide contains a description of the boss fight - Luctopus.
This opponent is encountered during Hollis' Hot Streak level.
Stage 1
The battle against Luctopus is rather simple and predictable.
Let’s start with the basics.
When the bomb is placed in a slot and explodes, the boss will be weakened for a while.
Once in that state, you’ve got the option to hit him further.
After evading thought bubbles, get behind the boss.
Destroy the board that blocks access to the boss’s head, and then focus on the heart.
Fire away and deprive him of as many health points as possible.
Stage 2
During Phase 2, Luctopus will receive new attacks, including throwable cards.
Proceed the same as before when the boss starts throwing bombs.
Repeat the whole process - jump on the thoughts and fight your way to the already tired heart.
Jump into the boss’s head and attack away with everything you got.
He can now electrify the entire floor - to avoid electrocution, you should probably jump on the chips.
Time for the final push - jump on the thoughts and start attacking the already exhausted and damaged heart.
You will be able to deprive the boss of the remaining health during this approach.
