Culling the Weak
{B}
Instant
Oracle Text
As an additional cost to cast this spell, sacrifice a creature.
Add {B}{B}{B}{B}.
Watch Out
Mana abilities don't use the stackRules Note
If this card's activated ability produces mana and doesn't target, it's a mana ability. Mana abilities resolve immediately without using the stack — opponents can't respond to them. However, abilities that target (even if they produce mana) aren't mana abilities.