Viashino Bladescout

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, target creature gains first strike until end of turn.

Green Slime

Flash
When this creature enters, counter target activated or triggered ability from an artifact or enchantment source. If a permanent's ability is countered this way, destroy that permanent.
Foretell {G} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Sulfur Elemental

Flash
Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
White creatures get +1/-1.

Activated Sleeper

Flash
You may have this creature enter as a copy of any creature card in a graveyard that was put there from the battlefield this turn, except it's a Phyrexian in addition to its other types.

Unrooted Ancestor

Flash
{1}, Sacrifice another creature: This creature gains indestructible until end of turn. Tap it. (Damage and effects that say "destroy" don't destroy it.)

Simian Grunts

Flash
Echo {2}{G} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)

Spire Mangler

Flash
Flying
When this creature enters, target creature you control with flying gets +2/+0 until end of turn.

Fire Nation Ambushers

Flash (You may cast this spell any time you could cast an instant.)

Spirit of the Hunt

Flash
When this creature enters, each other creature you control that's a Wolf or a Werewolf gets +0/+3 until end of turn.

Agent Venom

Flash
Menace
Whenever another nontoken creature you control dies, you draw a card and lose 1 life.

Wolfir Avenger

Flash (You may cast this spell any time you could cast an instant.)
{1}{G}: Regenerate this creature.

Opposition Agent

Flash
You control your opponents while they're searching their libraries.
While an opponent is searching their library, they exile each card they find. You may play those cards for as long as they remain exiled, and you may spend mana as though it were mana of any color to cast them.

Vile Redeemer

Devoid (This card has no color.)
Flash
When you cast this spell, you may pay {C}. If you do, create a 1/1 colorless Eldrazi Scion creature token for each nontoken creature that died under your control this turn. Those tokens have "Sacrifice this token: Add {C}."

Swarm, Being of Bees

Flash
Flying
Mayhem {B} (You may cast this card from your graveyard for {B} if you discarded it this turn. Timing rules still apply.)

Pouncing Cheetah

Defender of Chaos

Boon Satyr

Flash
Bestow {3}{G}{G} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
Enchanted creature gets +4/+2.

Ambush Wolf

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, exile up to one target card from a graveyard.

Endurance

Flash
Reach
When this creature enters, up to one target player puts all the cards from their graveyard on the bottom of their library in a random order.
Evoke—Exile a green card from your hand.

Swift Warden

Flash
When this creature enters, target Merfolk you control gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Nimana Skydancer

Flash
Flying
When this creature enters, target opponent mills two cards. (They put the top two cards of their library into their graveyard.)

Guardian Augmenter

Flash
Commander creatures you control get +2/+2.
Commanders you control have hexproof.

Sandstalker Moloch

Flash
When this creature enters, if an opponent cast a blue and/or black spell this turn, look at the top four cards of your library. You may reveal a permanent card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Sautekh Immortal

Flash
Elite Troops — This creature enters with a +1/+1 counter on it for each creature that died this turn.

Yurlok of Scorch Thrash

Vigilance
A player losing unspent mana causes that player to lose that much life.
{1}, {T}: Each player adds {B}{R}{G}.

Dualcaster Mage

Flash
When this creature enters, copy target instant or sorcery spell. You may choose new targets for the copy.

Gluttonous Slime

Flash
Devour 1 (As this creature enters, you may sacrifice any number of creatures. It enters with that many +1/+1 counters on it.)

Caller of the Claw

Flash
When this creature enters, create a 2/2 green Bear creature token for each nontoken creature put into your graveyard from the battlefield this turn.

Hired Blade

Raging Kavu

Appendage Amalgam

Flash
Whenever this creature attacks, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Bounding Wolf

Lobelia Sackville-Baggins

Flash
Menace
When Lobelia enters, exile target creature card from an opponent's graveyard that was put there from the battlefield this turn, then create X Treasure tokens, where X is the exiled card's power.

Liliana's Standard Bearer

Flash
When this creature enters, draw X cards, where X is the number of creatures that died under your control this turn.