hard mode variants of bosses

I'm trying to replace (don't mind the sprite it is related) but it won't work. any help pls??

i finally did it. 1 to go......

Dev Update - December 2024

are these better SBN lap 3 tv's?

Spring Cleaning - April 2025

my malformed son. lenny r. sound

Updated stuff

Dev Update - April 2024

Strongcold Titlecard