msem-instigator

If a source you control would deal damage this turn, it deals double that damage instead.
Coalesce {7}{R}{R} (You may cast this from your graveyard for {7}{R}{R}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Haste

Vanishing 3 (This permanent enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
Whenever a time counter is removed from Thespian's Finale, create a token that's a copy of target creature. Sacrifice that token at the beginning of your next upkeep.

Flying
Whenever Theurgic Flock deals combat damage to a player, if it doesn't have a +1/+1 counter on it, put a +1/+1 counter on it.

Whenever Thicketkeeper perseveres, add {G}{G}. Until end of turn, you don't lose this mana as steps and phases end. (A creature perseveres when it survives damage.)

Choose two —
• Scry 3, then you may mill up to three cards.
• Each opponent loses 3 life.
• You draw a card and you lose 1 life.
• Return a creature card from your graveyard to your hand.

First strike
Other Foxes you control get +1/+1.
Whenever a Fox you control becomes blocked, it deals 1 damage to each creature blocking it.

Draw three cards. Then discard two cards unless you discard a card that has the same name as a permanent you control or a card in your graveyard.

Draw three cards. Then discard two cards unless you discard an instant or sorcery card.

Draw three cards, then discard two cards unless you discard a multicolored card.

Rhapsody {4}{U}{U} (Pay {4}{U}{U} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Whenever you draw a card, any number of target players mill two cards.
Whenever This Is Not Our Fate deals combat damage to a player, for each player, you may cast an instant or sorcery card from that player's graveyard 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.)

When Thorn Tender enters, rouse 1, then put a +1/+1 counter on each creature you control. (Put a +1/+1 counter on a permanent you control. If it isn't a creature, tap it and it becomes a 0/0 creature in addition to its other types.)

Other untapped creatures have hexproof.
Whenever a creature attacks you, put a +1/+1 counter on a creature you control.

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

Whenever a creature enters under an opponent's control, draw a card unless that player pays {1}.

Untap target creature and gain control of it until end of turn. That creature gains haste until end of turn.

Attacking creatures get +2/+0 until end of turn.
Armed — Equipped creatures you control get an additional +1/+0 until end of turn.

Reveal the cards in your library. Target opponent chooses three nonland cards with different names from it. You put the chosen cards into your hand. Then shuffle.

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

Target creature gets -3/-3 until end of turn. Its controller loses 3 life. You mill three cards.

When Threshing Sundew enters, merge up to one target creature card in your graveyard under it. Threshing Sundew has that card's abilities.
When Threshing Sundew dies, return all other cards merged with it to their owner's hand.

Vigilance, trample
When Threshold Guardian enters, return a creature you control to its owner's hand.

Whenever Thrinax Sporemother or another nontoken creature you control dies, create a 1/1 green Saproling creature token.
Whenever a creature card is exiled from your graveyard, create a 1/1 green Saproling creature token.

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.)
Thuggish Detective can't be blocked by more than one creature.
When Thuggish Detective becomes renowned, you may destroy target noncreature permanent.

Augmented — When you cast this spell, if it's your turn and you've spent {W}{U}{B}{R}{G} to cast spells this turn, copy it twice. You may choose new targets for the copies.
Thunder Road deals 3 damage to any target. You gain 3 life.