msem-instigator

Thunder Wave deals 3 damage to target creature or planeswalker.

Target creature gets +1/+1 for each creature you control and gains flying and vigilance until end of turn.

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.

Whenever Thundering Towershell attacks, return a creature card with mana value 5 or less from a graveyard to the battlefield under your control. Trigger a death knell of that creature.

Wu Xing (Add effects based on the number of colors of mana spent to cast this spell.)
1 | Attacking creatures get -3/-0 until end of turn.
3 | Thundering Wrath deals 1 damage to each of those creatures.

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.)

Flash
Cycling {2} ({2}, Discard this card: Draw a card.)

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

Primal {2}{R}{R} (During your turn, you may cast this spell for {2}{R}{R} instead of playing a land.)
Flying, prowess
At the beginning of your end step, if you didn't cast a spell this turn, sacrifice Thunderstride.

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.

Creature tokens you control get +1/+1.
Whenever Thyra, Winter's Warden enters or attacks, you may pay {1}{G/W}. If you do, create Bruga, a legendary 2/2 green and white Wolf creature token.

Flying
Tianyuren Skycharter has hexproof as long as you control a storied permanent. (Enchantments and legendary permanents are storied.)

Choose one —
• Draw three cards, then discard a card.
• The owner of target nonland permanent puts it on the top or bottom of their library.

Flash
Menagerie — When Tidal Trickster enters, if there are five or more creature types among creatures you control, you may search your library for a card named Tidal Trickster, reveal it, put it into your hand, then shuffle.

Whenever Tide Crasher attacks, if you control another Merfolk, tap target creature defending player controls.

Lionize {1}{U} ({1}{U}, Exile this card from your hand: Put a +1/+1 counter on target creature and it gains the following ability until end of turn. You may cast this card on a later turn from exile.)
Sacrifice this creature: Counter target instant or sorcery spell unless its controller pays {X}, where X is this creature's power.

When this creature enters, return a creature you control to its owner's hand.
{2}{U}: This creature gets +2/-2 until end of turn.

Permanents you control gain indestructible until end of turn. Untap each creature you control.
Cycling {W} ({W}, Discard this card: Draw a card.)

Choose target creature you control and target creature you don't control. Flip a coin. If the coin comes up heads, put one of those creatures on top of its owner's library. Otherwise, put both of them on top of their owners' libraries.