msem-instigator

You may reveal creature cards with mana value 3 or less as you draw them. Once each turn, when you reveal a card this way, you may aetherize it. (To aetherize, create a token that's a copy of it, then exile that token.)

Whenever a creature attacks you or a planeswalker you control, that creature doesn't untap during its controller's next untap step.

At the beginning of your upkeep, you may exile a card from your hand. If you do, draw a card.
Whenever equipped creature deals combat damage to a player, you may put a card exiled with Travel Pouch into its owner's hand.
Equip {1}

{1}, Sacrifice Traveler's Amulet: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Treacherous Den enters tapped.
{T}: Add {B} or {R}.
{2}{B}{R}, {T}, Sacrifice Treacherous Den: Draw a card.

{T}: Add {C}.
{3}, {T}, Sacrifice Treasure Beach: Create three Treasure tokens. (They have “{T}, Sacrifice this artifact: Add one mana of any color.”)

As Tree of Timelines enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {B}, {G}, or {U}.

Equipped creature has menace.
Whenever equipped creature attacks, look at the top two cards of your library. Put any number of them into your graveyard and the rest back on top of your library in any order.
Equip {2}

{T}, Pay 1 life: Add {G}.
{T}, Pay 1 life, Sacrifice Tropical Grove: Search your library for a Forest card, put it onto the battlefield tapped, then shuffle.

Tsubasa's Redoubt enters tapped.
When Tsubasa's Redoubt enters, you may mill two cards.
{T}: Add {W} or {B}.

{2}, {T}, Sacrifice Tunnel Map: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Twisting Fissure enters tapped.
{T}: Add {U} or {R}.
{1}, {T}: Add one mana of any color.

You may play Typhoon Caverns from your graveyard as long as seven or more cards are in your graveyard.
Typhoon Caverns enters tapped.
{T}: Add {U} or {B}.
Cycling {1}{U}{B} ({1}{U}{B}, Discard this card: Draw a card.)

{T}: Add {C}.
{3}{B}: Until end of turn, Tzhai's Throne becomes a 2/2 creature. It's still a land. It gets +2/+2 if {R} was spent to activate this ability, gets +2/+2 if {G} was spent, and gets +2/+2 if {W} was spent.

Uncharted Haven enters tapped.
As Uncharted Haven enters, choose a color.
{T}: Add one mana of the chosen color.

When Uncovered Idol enters, scry 1.
{1}, Sacrifice Uncovered Idol: Put a +1/+1 counter on target creature. Activate only as a sorcery.

When Unity Spheres enters, create two 1/1 colorless Construct artifact creature tokens.
Tap two untapped creatures you control: Add two mana of any one color.

University Archive enters tapped.
When University Archive enters, look at the top card of your library. You may put it into your graveyard.
{T}: Add {U} or {R}.

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

{T}, Pay 1 life: Add {U} or {B}.
{1}, {T}, Sacrifice Unlit Alley: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

When Unmarked Vials enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
{1}, {T}: Add one mana of any color.

Vanishing 2 (This permanent enters with two time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
{T}: Add {C}.
When Unstable Footing is put into your graveyard from the battlefield, if it had no time counters on it, search your library for a basic land card, put it onto the battlefield, then shuffle.

When Unstable Orb enters, draw a card.
{3}, {T}, Sacrifice Unstable Orb: It deals 2 damage to target creature.

{T}: Add {C}.
{T}, Sacrifice Untethered Spire: Choose target land card in your graveyard that was put there from the battlefield this turn. Return that card to your hand.

Untrekked Territory enters tapped.
{T}: Add {B} or {G}.
When Untrekked Territory enters, you may put a loyalty counter on a planeswalker you control.