msem-instigator

Flying
Suisei the Southern Star gets +1/+1 for each comet counter you have.
Whenever you cast an instant or sorcery spell with mana value greater than the number of comet counters you have, you may pay {R}. If you do, return Suisei from your graveyard to the battlefield, then you get a comet counter.

{W}: Target creature gains vigilance until end of turn.

Primal {1}{W}{W} (During your turn, you may cast this spell for {1}{W}{W} instead of playing a land.)
Double strike
When Sunken Slasher enters, if you didn't play a land this turn, put a +1/+1 counter on it.

Flying, haste
Assault {1}{R} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
Whenever one or more +1/+1 counters are put on a creature you control, you may return Sunnula's Firebird from your graveyard to your hand.

Haste
Ward—Pay 3 life.
Whenever Surface Expeditioneer attacks, if it's embattled, it deals 2 damage to target player or planeswalker. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

Whenever Swift-Fingered Sneak enters or attacks, you may discard a card. If you do, draw a card.

Haste
Whenever Tailor of Terror attacks, you may exile a creature card from your graveyard. If you do, put a +1/+1 counter on Tailor of Terror.

First strike
Whenever Takeda Taro deals combat damage to an opponent, it deals 1 damage to each creature and planeswalker that player controls.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Whenever The Dreamer enters or you play a card exiled with them, exile the top two cards of your library face down, then another face up.
You may play face up cards exiled with The Dreamer.
{T}, Sacrifice The Dreamer: Look at each face down card exiled with The Dreamer. You may cast one without paying its mana cost.

Other creatures have haste and attack each combat if able.
Nonland cards in your hand have paranoia {4}. (The owner of a card with paranoia {4} may cast it from their hand for {4} when a permanent they control leaves the battlefield.)

Flying
Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{3}{R}{R}, {T}: Exile an instant card with mana value 3 or less from your graveyard, then cast a copy of a card exiled with Thunderlash Mystic without paying its mana cost.

Harmony — Creatures you control gain double strike until end of turn.
When Twirling Duet enters, harmonize. (Trigger up to one harmony of one permanent you control.)

This spell costs {2} less to cast if your starting deck contained at least forty cards more than the minimum deck size.
When Unrivaled Fireweaver enters, you may exile a red instant or sorcery card you own from outside the game. Until the end of your next turn, you may play that card.

Renown 1 (When this creature deals combat damage to a player, if it isn't renowned, put a +1/+1 counter on it and it becomes renowned.)
Whenever a creature you control becomes renowned, create a 1/1 red Soldier creature token with haste.

Flying, haste
{R}: Varagan Wyrmling gets +1/+0 until end of turn. Activate this ability only up to three times each turn.

Flying, haste
Venwyn, the Dragon's Fang can't block.
At the beginning of combat on your turn, you may pay {1}{R/G}. If you do, create a token that's a copy of target creature you control with mana value 3 or less, except it's not legendary and has haste. Exile that token at end of combat.

Rhapsody {3}{R}{R} (Pay {3}{R}{R} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Whenever Vindictive Guardian or another creature you control enters, if that creature's power is 4 or greater, create a Treasure token.

When Visiting Dignitary enters, gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn.

Eureka! (At the beginning of each end step, you get a research counter if you cast a spell this turn. Then if you have eight or more research counters, remove them and create a Masterpiece token of your choice.)
Whenever an artifact you control enters, up to two target creatures get +1/+0 and haste until end of turn.

When Wavebreaker enters, add two mana of any one color. You can't spend this mana to cast spells.

Whenever you cast a Knight spell or an Adventure spell, Wimbledon's Squire gets +1/+1 until end of turn.

(Transcend as a sorcery to gain that type and a +1/+1 counter.)
Trample
{2}{R}: Demigod
Create a 2/1 black Spirit creature token with “This creature can't block.”
{5}{R}: God
Until end of turn, creatures you control get +1/+0 and gain haste and “When this creature dies, it deals 1 damage to any target.”

At the beginning of combat on your turn, you may pay {2}{R}{R}. If you do, create a 4/4 red Dragon creature token with flying and haste. Exile that token at end of combat.
Ferocious — Whenever Xiusheng of the Dragon Realm attacks, if you control a creature with power 4 or greater, Xiusheng gains double strike until end of turn.

Flying
Erratic (When this creature dies, reveal the top four cards of your library. Put a creature card that costs less than this revealed this way onto the battlefield and the rest on the bottom of your library in any order.)
Whenever Zaidha, Seraph of Calamity deals combat damage to a player, choose up to two target nonland permanents that player controls and target nonland permanent you control. Destroy one of those permanents at random.