Sacrifice a land: Trenching Steed gets +0/+3 until end of turn.

Whenever equipped creature attacks, defending player reveals cards from the top of their library until they reveal a land card. The creature gets +1/+0 until end of turn for each card revealed this way. That player puts the revealed cards into their graveyard.
Equip

: Trespassing Souleater can't be blocked this turn. ( can be paid with either or 2 life.)

Return all creatures blocking or blocked by target creature to their owner's hand.

When Trial of Knowledge enters the battlefield, draw three cards, then discard a card.
When a Cartouche enters the battlefield under your control, return Trial of Knowledge to its owner's hand.

When Trial of Solidarity enters the battlefield, creatures you control get +2/+1 and gain vigilance until end of turn.
When a Cartouche enters the battlefield under your control, return Trial of Solidarity to its owner's hand.

, Sacrifice Triangle of War: Target creature you control fights target creature an opponent controls. (Each deals damage equal to its power to the other.)

, : Put a hatchling counter on Triassic Egg.
Sacrifice Triassic Egg: Choose one —
• You may put a creature card from your hand onto the battlefield. Activate this ability only if two or more hatchling counters are on Triassic Egg.
• Return target creature card from your graveyard to the battlefield. Activate this ability only if two or more hatchling counters are on Triassic Egg.

When Tribute Mage enters the battlefield, you may search your library for an artifact card with converted mana cost 2, reveal that card, put it into your hand, then shuffle your library.

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Counter target activated or triggered ability. If a permanent's ability is countered this way, activated abilities of that permanent can't be activated this turn. (Mana abilities can't be targeted.)

Choose one —
• Target creature gains flying until end of turn.
• Target creature becomes the creature type of your choice until end of turn.
• Look at the top four cards of your library, then put them back in any order.

Enchant creature
Enchanted creature gets +2/+0 and can't be blocked.

, , Discard a card: You may tap or untap target artifact, creature, or land.

Flash
Enchant creature
When Triclopean Sight enters the battlefield, untap enchanted creature.
Enchanted creature gets +1/+1 and has vigilance.

Trigon of Mending enters the battlefield with three charge counters on it.
, : Put a charge counter on Trigon of Mending.
, , Remove a charge counter from Trigon of Mending: Target player gains 3 life.

Trigon of Thought enters the battlefield with three charge counters on it.
, : Put a charge counter on Trigon of Thought.
, , Remove a charge counter from Trigon of Thought: Draw a card.

As long as Trinisphere is untapped, each spell that would cost less than three mana to cast costs three mana to cast. (Additional mana in the cost may be paid with any color of mana or colorless mana. For example, a spell that would cost to cast costs to cast instead.)

When Trinket Mage enters the battlefield, you may search your library for an artifact card with converted mana cost 1 or less, reveal that card, and put it into your hand. If you do, shuffle your library.

, : Tap target creature.

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for or one mana of that creature's color.)
Create three 1/1 white Spirit creature tokens with flying. (They can't be blocked except by creatures with flying or reach.)