Crackling Night

Creatures you control have haste.
Dash {2}{b}{b}{r}{r} (You may cast this spell for its
dash cost. If you do, it gains haste, and it's returned
from the battlefield to its owner's hand at the
beginning of the next end step.)
When Crackling Night leaves the battlefield,
destroy up to X target creatures, where X is
half the number of tapped creatures you
control, rounded up.