+Mesmeric (7)
Flying
When Mesmeric Fiend enters, target opponent reveals their hand and you choose a nonland card from it. Exile that card.
When Mesmeric Fiend leaves the battlefield, return the exiled card to its owner's hand.
Counter target spell with mana value 3 or less. (Then exile this card. You may cast the creature later from exile.)
Whenever a permanent becomes untapped, that permanent's controller mills a card.
All Slivers have "When this permanent enters, you may fateseal 1." (To fateseal 1, its controller looks at the top card of an opponent's library, then they may put that card on the bottom of that library.)
Cumulative upkeep (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
, Discard a card: Draw a card.
Flying, deathtouch
When CARDNAME enters the battlefield, target opponent chooses an order for the cards in their hand, then reveals them one by one until you say stop. That player then discards the most recently revealed card.
Gatherer works better in the Companion app!
(At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
, Discard a card: Draw a card.