Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.

Flash
If a nontoken creature would enter and it wasn't cast, exile it instead.

If an opponent would mill one or more cards, they mill twice that many cards instead. (To mill a card, a player puts the top card of their library into their graveyard.)

Return from your graveyard to the battlefield any number of target creature cards that each have a different mana value X or less.

All Sliver creatures get +1/+1 for each other Sliver on the battlefield.

: Add .
: Add one mana of any color. Spend this mana only to cast a legendary spell.
: Add one mana of any color among legendary permanents you control.
, , Exile this land: Target legendary creature gains hexproof and indestructible until end of turn.

Flying
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
At the beginning of combat on your turn, choose up to one target creature you control. Until end of turn, that creature gets +2/+0, gains trample if it's red, and gains vigilance if it's white.

When The Meathook Massacre enters, each creature gets -X/-X until end of turn.
Whenever a creature you control dies, each opponent loses 1 life.
Whenever a creature an opponent controls dies, you gain 1 life.

Flying
Your opponents can't gain life.
At the beginning of each end step, each opponent loses life equal to the life that player lost this turn. (Damage causes loss of life.)

When you cast this spell, exile up to one target permanent that's one or more colors.
Whenever you cast a colorless spell, exile up to one target permanent that's one or more colors.
+2: You gain 3 life and draw a card.
0: Add .
−11: Search your library for any number of colorless nonland cards, exile them, then shuffle. Until end of turn, you may cast those cards without paying their mana costs.

Equipped creature has menace, deathtouch, annihilator 1, and "Whenever an opponent sacrifices a nontoken permanent, put that card onto the battlefield under your control unless that player pays 3 life." (Whenever a creature with annihilator 1 attacks, defending player sacrifices a permanent of their choice.)
Equip

Trample, infect, indestructible
If Blightsteel Colossus would be put into a graveyard from anywhere, reveal Blightsteel Colossus and shuffle it into its owner's library instead.

Trample, haste
At the beginning of the end step, sacrifice this creature.
Morph (You may cast this card face down as a 2/2 creature for . Turn it face up any time for its morph cost.)

Flying, trample
Pay 2 life, Sacrifice another creature: Search your library for a card, put that card into your hand, then shuffle.

Target creature gets -X/-X until end of turn, where X is the number of times the letter of your choice appears in that creature's name.

Whenever a non-Human creature you control attacks, look at the top six cards of your library. You may put a Human creature card from among them onto the battlefield tapped and attacking. It gains indestructible until end of turn. Put the rest of the cards on the bottom of your library in a random order.

(: Add .)

: Add two mana in any combination of , , and/or .
, : Draw two cards, then discard a card.

Whenever you cast an artifact, instant, or sorcery spell, copy that spell. You may choose new targets for the copy. This ability triggers only once each turn. (A copy of a permanent spell becomes a token.)
Whenever an opponent casts an artifact, instant, or sorcery spell, counter that spell. This ability triggers only once each turn.

( can be paid with either or 2 life.)
, , Sacrifice a creature: Search your library for a creature card with mana value equal to 1 plus the sacrificed creature's mana value, put that card onto the battlefield, then shuffle. Activate only as a sorcery.