msem-instigator

Haste
Whenever Spotted Slugger deals combat damage to a player, you may have it deal damage equal to its power to target creature.

When Stalwart Physicker enters, you may remove a -1/-1 counter from target creature.

Flash (You may cast this spell any time you could cast an instant.)
When Stampede Instigator enters, target creature gets +2/+3 until end of turn.

Whenever Steelcrusher Viking blocks or becomes blocked by a creature, destroy up to one target Aura or Equipment attached to that creature.

When Steward of Empire's Cradle enters, you may search your library for a Discovery, Quest, or Saga card, reveal it, then shuffle and put that card on top.
Civilized — If an ability of an enchantment you control triggers, if you control an artifact, a creature and an enchantment, that ability triggers an additional time.

{2}{G}: Look at the top three cards of your library. You may reveal a creature or Revelation card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Whenever a creature you control becomes the target of a spell, that creature gets +3/+3 until end of turn.

Whenever Swiftspear Ambusher and exactly one other creature attack, put a +1/+1 counter on target attacking creature.

Vigilance
Whenever a legendary creature you control enters, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Vigilance, reach
Tahti, Forged by the World gets +1/+1 for each other creature you control.
Other creatures you control get +1/+1.

{G}, {T}: Create a 1/1 green Elf creature token.
{3}{G}{G}, {T}: Create a 3/3 green Beast creature token.

When Tamer of the Ton dies, create a 4/4 green Chimera creature token.

{2}{U}, {T}: Reveal the top two cards of your library. Put all land cards revealed this way onto the battlefield and the rest into your graveyard.

Flash
Reach
Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)

{G}{G}, {T}: Create a token that's a copy of target creature you control that entered this turn, except it's an artifact in addition to its other types.

{T}: Put a +1/+1 counter on Tender of Gardens. Activate only as a sorcery.

When Tender of the Land enters, if you control four or more lands, draw a card.

Trample
Stampede — Whenever Thoctar Yearling and a creature with greater power attack, put a +1/+1 counter on Thoctar Yearling.

Flash
When Thornweald Cavalier enters, target creature gets +1/+1 until end of turn. Put a reach counter on it.

Whenever a creature you control phases in, it gets +2/+2 until end of turn.

Gestalt (When this or another creature enters under your control, you may merge it with the one in play, keeping counters and attachments. They become the permanent on top plus all abilities from under it.)
Hexproof
At the beginning of your upkeep, put a +1/+1 counter on this creature.

Trample
Once each turn, 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 Thunderwhirl Dancer enters, it gets +X/+X until end of turn, where X is the number of +1/+1 counters among creatures you control. Then it fights up to one target creature.

This spell has flash as long as you control a Soldier.
When Tinyvale Watchkeep enters, untap target creature.

Identity — At the beginning of your upkeep, if you control at least two other creatures that share a creature type with Trupi Coordinator, you may draw a card.