Stygius, Necrotic Dragon

Flying, Deathtouch
Convoke, delve (Each creature you tap while
casting this spell pays for 1 or one mana of that
creature's color. Each card you exile from your
graveyard pays for {1}.)
Every time Stygius, Necrotic Dragon attacks,
deals damage or is dealt damage, create
a 1/1 black Zombie token.