Lord Henry, the Poisoner

Menace, Haste
Whenever Lord Henry, the Poisoner attacks, gain
control of target creature until the end of your next
turn. It gains toxic X where X is that creature's
mana value.
Whenever a creature dies, its controller chooses one:
-Proliferate.
-Draw a card, then discard a card.
-Create a tapped treasure token and lose 1 life.