The Delta Rune

Indestructible, Shroud This enchantment enters with a +1/+1 counter for each {B} spent to cast it, and a -1/-1 counter on it for each {W} spent to cast it Each other non-creature permanent becomes a 0/0 Black Nightmare creature in addition to their other types as long as they have more +1/+1 counters on them than -1/-1 counters. {1}{B}: Put a +1/+1 counter on each non-creature permanent and each nightmare. If there are 15 or more +1/+1 counters on this Enchantment, destroy all nightmare creatures. {1}{W}: Put a -1/-1 counter on each non-creature permanent and nightmare creature. Any player may activate this ability.