You said SP , The SP draining card is Dark Priest which has a false stack - the chance remains same but the SP drained stacks.
Abyss is 30% on bosses - I don't use this card so I do not have an idea.
Does that mean if you get a Dp,Dp,Dp,Dp Mg you still get 5% chance, but if it works, it takes 40% of his Sp instead? =o
Edit@ And does Dark Priest card work with bow? Anyone?