Monsters are invincible/Algorithm question???

Since I changed the magic formula to half all magic damage, the monster version of it has been taken into account:

Damage = Spell Power * 2 + (Level * (Magic Power * 3/2) * Spell Power / 64)

The info on attacker IDs were very helpful. Thank you!

The X register usually holds the attacker ID, a number from $00 to $14, for each of the ten possible entities in battle. For PCs it is $00, $02, $04, or $06, so CPX #$08 and BCC is often used to differentiate between characters and monsters. For targets, the Y register is used instead.

I actually have a question about this. I suspect there are quite a bit of "ID" numbers that I'm unaware of. Where can I look to find out this sort of stuff? Are those variables stored in the banks like all the other information or are there other documents I should be looking at?

There are no notes or guides on how the code works besides the commented disassemblies. You'll have to figure this stuff out from reading those, I'm afraid. The RAM map in on the wiki is another great resource!