msem-instigator

Create two 1/2 blue Bird creature tokens with flying.
Coalesce {5}{U}{U} (You may cast this from your graveyard for {5}{U}{U}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)

Trample
When Contentious Yak enters, another target creature you control gets +1/+1 and gains trample until end of turn.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
Cycling {U} ({U}, Discard this card: Draw a card.)

Vigilance, trample
Whenever you draw your second card each turn, put a +1/+1 counter on Coralblade Cohort.
Cycling {G} ({G}, Discard this card: Draw a card.)

{3}{W}: Tap target creature. Activate only during your turn.

Concord — When Coralight Communer enters, if there are four or more card types among permanents you control, draw a card.

Whenever another Zombie you control enters, you may pay {1}{B}. If you do, exile target creature card from a graveyard. You gain life equal to its toughness.

Whenever another Zombie or Demon creature you control enters, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

Menace
Sacrifice another creature: Corpulent Gibberer deals 1 damage to any target.
Evoke {1}{R} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Corsair Sellsword can't block.
Whenever you foretell a card or cast a foretold spell, you may return Corsair Sellsword from your graveyard to your hand.

Reach
Improve {1}{G/W} ({1}{G/W}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on that creature instead.

When Cosmonaut Pioneer enters or leaves the battlefield, choose one—
• Scry 1, then draw a card.
• Create a 3/3 green Alien creature token with trample.
• You gain 5 life.

Alpha (You may have this creature enter with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)
Flying
{2}{W}: Prevent all damage that would be dealt to and dealt by creatures with counters on them this turn.

Sacrifice a creature: Each opponent loses 1 life and you gain 1 life.
Sacrifice two creatures: Draw a card.
Sacrifice three creatures: Exile target creature or planeswalker.

Adorned — Coven Adherent has indestructible as long as it's equipped and/or enchanted.

Prowess
When Cramming Student enters, conjure ten cards named Fatigue and shuffle them into your library. (They're colorless sorceries that cost {2} and have “Draw a card.”)
Instant and sorcery spells you cast cost {1} less to cast.

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
{2}{G}: Crazed Sprareos gets +2/+2 until end of turn. Activate only once each turn.

Bloodprice—Reappropriate red. (You may cast this spell by sacrificing a creature and exiling two red cards from your hand and/or graveyard.)
Haste
Whenever Creed's Desperado attacks, if defending player has more cards in hand than you, exile the top card of that player's library. You may cast it as long as you control a Warrior, and you may spend mana as though it were mana of any color to cast it.

First strike
Whenever Creed, Eternal Straggler attacks, exile the top card of your library. You may play that card this turn, and that spell costs {2} less to cast.

Whenever Crescent Crasher attacks, put a +1/+1 counter on target attacking creature with lesser power.

Flying
Wanderlust — When Crest Skimmer enters, if you control four or more differently named lands, draw a card.

Flying
Death knell — Put a flying counter on target creature you control. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)

Flying, haste
When Crimson Hellmaw enters, it deals 3 damage to any target.
Revive {5}{R}{R} ({5}{R}{R}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Vigilance
Crinster Ranger enters with X +1/+1 counters on it, where X is the number of +1/+1 counters among other creatures you control.

Flying
Whenever an embattled creature you control attacks, tap target creature defending player controls. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)