Right now, abilities drain is handled using the same Opcode that increases the attributes.
The problem: by PnP, there should exist several ways to prevent ability score draining from, let's say a shadow. And many creatures should be immune to it. None of those can be properly translated to IE because blocking the ability drain also blocks the ability buff. So the same effect that protects against the shadow attack also blocks Champion's Strength.
P1: Ability (0 - All, 1 - Str, 2 - Dex, 3 - Con, 4 - Int, 5 - Wis, 6 - Cha)
P2: Value (this Opcode accepts positives values only)
Special: (0 - Only Drain, 1 - Drain to Caster).
Now a shadow attack can be blocked through Opcode 101 using parameter X.
Undead may have their scores preserved through Opcode 324.
Everyone is happier.