msem-instigator

Thunder Wave deals 3 damage to target creature or planeswalker.

This spell costs {X} less to cast, where X is the greatest power among creatures you control.
Trample

Create a 3/3 red Giant creature token with haste.
Creatures you control gain double strike until end of turn.

Vanguard — Whenever a creature you control attacks alone, it gets +1/+1 and gains menace until end of turn.

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.

Thunderous Applause deals damage to any target equal to the number of tapped creatures you control.

Vigilance, menace, trample, haste
Whenever you cast a spell, you may have Thunderous Avarice consume. If you do, put a +1/+1 counter on it. (To consume, sacrifice another creature or exile a creature card from your graveyard.)
Whenever an opponent casts a spell, they may have Thunderous Avarice consume. If they don't, put a +1/+1 counter on it.

Target creature gains hexproof and trample until end of turn. If Thunderous Charge was cast from exile, that creature gets an additional +4/+4 until end of turn.
Orchestrate {G}{G} (You may exile this card from your hand anytime you could cast a sorcery for its orchestrate cost. When you next resolve a spell, you may cast this from exile without paying its mana cost.)

When Thunderstep Ved enters, it deals 1 damage to any target.

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.

Whenever Thunderwolf attacks, exile the top card of your library. You may play that card this turn.

Untap target land. Scry 1. (To scry 1, look at the top card of your library. You may put that card on the bottom of your library.)
Fabled {3}{G}{G} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that land.)

Create X 0/1 green Plant creature tokens, then distribute X +1/+1 counters among any number of creatures you control.

When Tiller's Adze enters, draw a card.
Equipped creature gets +1/+1.
Equip {1}

As Timber Range enters, you may pay 2 life. If you don't, Timber Range enters tapped.
{T}, Sacrifice Timber Range: Search your library for a Mountain or Forest card, put it onto the battlefield, then shuffle.

Each opponent sacrifices an artifact or enchantment.
Showcase {2}{G}{G} (Then if you cast this for its showcase cost, create a 1/1 red Bard creature token that can't block and exile this. Whenever it attacks, you may cast a free copy of this.)

{16}, {T}: Time Cube gains “At the beginning of your end step, if it's not an extra turn, take three extra turns after this one” and loses this ability.

Target creature you control gets +4/+4 until end of turn.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

When Timecrafter Lafterii enters, choose target permanent with one or more time counters on it, then put two time counters on it or remove two time counters from it.

When you next cast an instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

Target permanent gains indestructible and hexproof until end of turn. Remove all -1/-1 counters from it.

{T}: Add {C}.
{4}, {T}, Sacrifice Timeworn Crags: Destroy target nonbasic land. This ability costs {1} less to activate for each nonbasic land you don't control.

Whenever a creature you control enters, Timid Thunderhorn gets +X/+X until end of turn, where X is that creature's power.

{3}: Put a +1/+1 counter on Tinkerer's Assistant.

{X}{2}, {T}, Sacrifice Tinkerer's Tools: Sacrifice an artifact. If you do, search your library for an artifact card with mana value less than or equal to the sacrificed artifact's mana value plus X. Put it onto the battlefield, then shuffle. Activate only as a sorcery.