Kaylux, Apex of Fear

Mutate {4}{u/r}{b}{b} (If you cast this spell for its
mutate cost, put it over or under target non-human
creature you own. They mutate into the creature on
top plus all abilities from under it.)
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Menace, Haste, Flying
Whenever this creature mutates, each opponent
discards their hand then loses life equal to the
number of cards they discarded this way, then
draws four cards.