just as the title says, i have this spell that consumes 20% of the HP but i want to make it like huskar's lifebreak in DotA where base of his hp%left as cost (preventing him from dying like with 60/2000 HP and that spell is like cost 20% of the remaining hp to cast therefore he won't die after casting with low hp) [sry i find it hard to explain this] and ends up dying if the caster has 20% or less HP