msem-instigator

Choose target permanent. Take an extra turn after this one. During that turn's untap step, permanents other than the chosen permanent phase out until end of turn. Exile Time Stands Still.

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.

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

Destroy target non-Xirix permanent. If that permanent had mana value 6 or greater, take an extra turn after this one.

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

{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.

First strike
If one or more creature tokens would be created under your control, for each of those tokens, you may create three 2/2 green Cat Warrior creature tokens instead.

First mate — Each nonland card in your starting deck is an artifact, a Pirate, or has “artifact,” “Treasure,” or “Pirate” in its printed rules text. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
Whenever Tinbeard of the Brine attacks, each opponent loses X life and you gain X life, where X is the number of artifacts you control plus the number of Pirates you control.

At the beginning of combat on your turn, tap Tinchor, put two +1/+1 counters on him, you draw a card, and you lose 1 life.
When Tinchor dies, put his counters on target Human you control.

When Tinker Tantrum enters and at the beginning of your upkeep, you may sacrifice an artifact. If you do, reveal cards from the top of your library until you reveal an artifact card with mana value X or less, where X is 1 plus the sacrificed artifact's mana value. Put that card onto the battlefield and the rest on the bottom of your library in a random order.

{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.

Tinyvale Treetops enters tapped unless you played it from exile.
{T}: Add {G} or {W}.

Advance {3}{B}{B} (Cast this for {3}{B}{B} to advance it as it enters. {3}{B}{B}: Advance this as a sorcery.)
Whenever Tireless Archivist advances, search your library for a card, put it into your hand, then shuffle.

Search your library for an artifact card with mana value X, where X is 1 plus the greatest mana value among artifacts you control, reveal it, put it into your hand, then shuffle.
You may cast Tireless Endeavor from your graveyard by sacrificing an artifact in addition to paying its other costs.

Vigilance
Permanent spells you cast cost {1} less to cast for each 1 damage Tireless Explorer has dealt to players this turn.

{T}: Add {C}.
{T}, Exile two cards from your graveyard: Add {R} or {W}.

Menace
Titan of Fallen Stars gets +1/+1 from -1/-1 counters instead of -1/-1.
When Titan of Fallen Stars enters, move any number of -1/-1 counters from creatures you control onto Titan of Fallen Stars.

{T}: Add {C}{C}. Spend this mana only to cast spells with mana value 5 or greater.

Nonstoried creatures lose all abilities and have base power and toughness 1/1. (Enchantments and legendary permanents are storied.)

{3}, Sacrifice Titanic Fossil: Mill three cards, then you may exile a card from your graveyard. You may cast a copy of the exiled card without paying its mana cost if the spell's mana value is 3 or less. Activate only as a sorcery.
{3}{U}{B}: Return Titanic Fossil from your graveyard to the battlefield transformed. Activate only during your turn.

Enchant creature without flying
Enchanted creature gets +10/+0 and attacks each combat if able.

When To Go Beyond enters, draw a card, then choose a card name.
{2}{U}: Reveal a card you own from outside the game with the chosen name and put it on top of your library.

Creatures you control get +1/+1.
{3}{W}{W}, Sacrifice To a Bright Future: Put a +1/+1 counter on each creature you control.

Foretell {1}{B} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)
Create two X/X black Zombie creature tokens with menace, where X is the number of nontoken creatures that died under your control this turn.

Chosen one ({W}{U}{B}{R}{G}: Transform this permanent.)
When Tomb Steward enters, search your library for a card and put it into your graveyard. Then shuffle.