msem-instigator

Flying
Whenever Revived Pterosaur deals combat damage to an opponent, that player discards a card.
{4}{B}{B}, Discard two cards: Return Revived Pterosaur from your graveyard to the battlefield tapped.

Deathtouch
Instant and sorcery spells you control have deathtouch.
{2}{B}: Exile target creature card from an opponent's graveyard, then create a 2/2 black Zombie creature token and put a +1/+1 counter on Saffrisa, Heir Apparent.

Flying
Improve—{1}{B/R}, Sacrifice a creature. ({1}{B/R}, Sacrifice a creature: 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.)
Whenever another creature you control dies, each opponent loses 1 life and you gain 1 life. If that creature was sacrificed, instead each opponent loses 2 life and you gain 2 life.

Flying
Glorious end — When Shattered Valkyrie dies, if it was tapped, draw a card for each creature that died this turn.
Sacrifice another creature: Shattered Valkyrie gains indestructible until end of turn.

Creatures with power less than Skull-Crowned Chief's power can't block.

Menace (This creature can't be blocked except by two or more creatures.)
Sacrifice another creature: Stingbrood Warlord gains deathtouch until end of turn.

Each player sacrifices a creature.
Coalesce {5}{B} (You may cast this from your graveyard for {5}{B}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)

Menace, haste
Whenever Tiger of the Drums attacks, choose one —
• Exile target opponent's graveyard.
• You draw a card and lose 1 life.
• Torment each opponent. (They lose 3 life unless they discard a card or sacrifice a nonland permanent.)

When Vagabones enters, look at the top two cards of your library. Put any number of them into your graveyard and the rest on top of your library in any order.

Whenever two or more creatures you control deal combat damage to a player, you lose 1 life and draw a card.

This spell costs {2} less to cast if you've cast both an instant spell and a sorcery spell this turn.
Haste

Whenever you cast a Pirate spell, create a 1/1 blue and red Pirate creature token with haste.

Menace
Whenever a creature blocks, put a -1/-1 counter on that creature at end of combat.
Creatures with -1/-1 counters on them can't block.

Haste
Whenever Arpechian Tiger attacks, you may sacrifice a land. If you do, Arpechian Tiger deals 3 damage to target creature or planeswalker.

Menace, haste
At the beginning of combat on your turn, gain control of up to two target noncreature, nonland permanents your opponents control until end of turn. Untap those permanents. You may attach any number of Equipment among them to creatures you control until end of turn. (They unattach at end of turn.)

Trample
Harmony — Avalanche Drummer deals 1 damage to any target.
When Avalanche Drummer enters, harmonize. (Trigger up to one harmony of a permanent you control.)

Frenzy 2 (Whenever this creature attacks and isn't blocked, it gets +2/+0 until end of turn.)
Blocked creatures you control have first strike.

Desecrate (When this creature enters, you may sacrifice an artifact or land.)
When Beastback Raider desecrates a permanent, discard your hand, then draw three cards.

Improve {1}{R} ({1}{R}: 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.)
As long as Bloodbelly Glutton is embattled, it has first strike, menace, and haste. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Bounty Crusher has trample as long as it's being blocked by a marked creature.

Wither (This deals damage to creatures in the form of -1/-1 counters.)

Deploy 3 (As this enters, you may tap any number of other creatures you control with total power 3 or more.)
When Coalition Alchemist enters deployed, return target instant or sorcery card from your graveyard to your hand.

Dominance — At the beginning of combat on your turn, if you control the creature with the greatest power or tied for the greatest power, you may pay {R}. If you do, gain control of target creature an opponent controls until end of turn. Untap that creature. It gains haste until end of turn.

When Dragonheart Seer dies, you may exile it. If you do, return up to two target instant and/or sorcery cards from your graveyard to your hand.

Menace, haste
Other Centaurs you control get +1/+0.