Gau's Rage 75%

The easiest way is to replace the coin flip with a call to the RNG function at $C24B5A to draw a random number 0..255, then compare it to 64 for a 75% chance to set the carry flag.

Edit: just do this

Code:

;header
!freespace = $c2a65a

org $c20600
jsr newfunc

org !freespace
newfunc:
sep #$20
jsr $4b5a
cmp #$40
rep #$20
rts

Copy the above code into notepad, save it as something.asm and look up on Youtube how to apply an ASM patch using xkas.