msem-instigator

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.)

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.

Embellish {3}{B} (If you cast this spell for {3}{B}, create a 1/1 blue Thopter artifact creature token with flying when it enters.)
Tidehollow Lich can't block.
You may cast Tidehollow Lich from your graveyard as long as you control an artifact creature.

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
When Tidepool Turtle has three or more +1/+1 counters on it, remove them all and transform it.

Vanishing 4 (This creature enters with four time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
Remove a time counter from Tideshift Elemental: You may tap or untap target creature.

Once each turn, when a creature you control becomes tapped, you may untap that creature and tap up to one target creature.

Kicker {X}{U} (You may pay an additional {X}{U} as you cast this spell.)
When Tidetwister Mage enters, if it was kicked, return all other creatures with power X or less to their owners' hands.

Menace, haste
Whenever Tiger of the Drums attacks, choose one —
• Exile target opponent's graveyard.
• You draw a card and lose 1 life.
• Torment each opponent. (They lose 3 life unless they discard a card or sacrifice a nonland permanent.)

Flying (This creature can't be blocked except by creatures with flying or reach.)
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.)

Enchant creature
When Til Death enters, exile target creature an opponent controls other than enchanted creature until Til Death leaves the battlefield.
Enchanted creature has defender.

Flying, prowess
Whenever you cast a noncreature spell, reveal the bottom two cards of your library. Target opponent chooses one of them. Put that card on the bottom of your library and the rest into your hand.

Whenever you cast your first noncreature spell each turn, you may draw a card. If you do, discard a card.

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.

Instant and sorcery spells you control have leitmotif. (Exile that spell as it resolves if you cast it from your hand. When you next cast a spell that shares a color with that card, you may cast it from exile without paying its mana cost.)

{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.

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.

({T}: Add {G} or {W}.)
Timeless Shrine enters tapped.
{1}, {T}: Add {G}{G} or {W}{W}.

Double strike (This creature deals both first-strike and regular combat damage.)
If three or more creatures are attacking you, you may cast Timely Commander as though it had flash.

Flying, lifelink
When Timestream Sentinel enters, put two +1/+1 counters on each other creature named Timestream Sentinel you control.