Halaster the Mad

Whenever you cast an instant or sorcery spell,
roll a d20.
1-5: Sacrifice a creature.
6-10: Copy target instant or sorcery spell.
You may choose new targets for the copy.
11-15: After target spell resolves, exile it. You
may cast it later from exile without paying its
mana cost.
16{dash}20: Create a token copy of Halaster the
Mad, except the token isn't legendary. Roll
another d20.