Giving Everyone the Same Desperation Attack

You could try using $3A56. A bit gets set for each character with Wound, Petrify, or Zombie status. See C2/46A9.

There's also a subroutine at C2/520E which counts the number of bits set in the accumulator. You could use this to get your multiplier. For example:

Code:

LDA $3A56 ; bit mask for number of dead characters (use 8-bit A to get characters only)
JSR $520E ; count bits set in A

; now X holds the number of dead characters
; you can use this to adjust the probability of getting a lv.2 desperation attack

There's also $3A76, which is a count of the number of characters that are alive. See C2/4AB9.