Légions

All Sliver creatures have provoke. (Whenever a Sliver attacks, its controller may have target creature defending player controls untap and block it...

Noncreature spells cost {1} more to cast.

Whenever Noxious Ghoul or another Zombie enters the battlefield, all non-Zombie creatures get -1/-1 until end of turn.

Cycling {3} ({3}, Discard this card: Draw a card.)

Whenever a Sliver deals damage, its controller gains that much life.

All Slivers have "{T}: Target Sliver creature gets +X/+0 until end of turn, where X is the number of Slivers on the battlefield."

Whenever a Sliver deals combat damage to a creature, destroy that creature. It can't be regenerated.

{1}{B}, {T}, Sacrifice a creature: Search your library for a Zombie card and a Swamp card, reveal them, put them into your hand, then shuffle.

{1}{U}: Change Riptide Mangler's base power to target creature's power. (This effect lasts indefinitely.)

All Slivers have "{1}: This permanent becomes the creature type of your choice in addition to its other types until end of turn."

{B}, Pay 1 life: Add one mana of any color.

Mistform Ultimus is every creature type (even if this card isn't on the battlefield).

First strike Provoke (Whenever this creature attacks, you may have target creature defending player controls untap and block it if able.)

Flash When Caller of the Claw enters the battlefield, create a 2/2 green Bear creature token for each nontoken creature put into your graveyard fro...

Flying Morph {6}{R}{R} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.) When Imperial Hel...

Flying When Havoc Demon dies, all creatures get -5/-5 until end of turn.

Defender (This creature can't attack.) {3}: Turn Wall of Deceit face down. Morph {U} (You may cast this card face down as a 2/2 creature for {3}....

Flying {T}: Prevent the next 2 damage that would be dealt to any target this turn.

Whenever a Sliver deals combat damage to a player, its controller may draw a card.

All Slivers have "{T}: Target Sliver creature gets +X/+0 until end of turn, where X is the number of Slivers on the battlefield."

{T}: Target creature gets +X/+X until end of turn, where X is the number of Elves on the battlefield.

Whenever a Sliver deals combat damage to a player, its controller may create a 1/1 colorless Sliver creature token.

Morph {4}{U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.) When Weaver of Lies is turn...

Covert Operative can't be blocked.