Mystery Booster 2

Serum Powder

{T}: Add {C}.
Any time you could mulligan and Serum Powder is in your hand, you may exile all the cards from your hand, then draw that many cards. (You can do this in addition to taking mulligans.)

Iconic Masters

{T}: Add {C} to your mana pool.
Any time you could mulligan and Serum Powder is in your hand, you may exile all the cards from your hand, then draw that many cards. (You can do this in addition to taking mulligans.)

Darksteel

{T}: Add {1} to your mana pool.
Any time you could mulligan and Serum Powder is in your hand, you may remove your hand from the game, then draw that many cards. (You can do this in addition to taking mulligans.)