msem-instigator

Protection from nonblue
Whenever Terror of Palta Gorge attacks, exile another target nonblue creature until Terror of Palta Gorge leaves the battlefield.

Flying, first strike
Whenever Terror of Sunset Cliffs attacks, each player discards their hand and draws seven cards.
Whenever an opponent discards a card, Terror of Sunset Cliffs deals 1 damage to that player.

Kicker {4}{U}{U} (You may pay an additional {4}{U}{U} as you cast this spell.)
Return target nonland permanent to its owner's hand. If this spell was kicked, create an 8/8 blue Kraken creature token with trample.

Puzzlebox (Begin the game with this and another card you own from outside the game in the command zone, locked. That card is face down until you unlock this.)
{0}: Unlock Tesseract Conjecture. If the revealed card shares a mana value with three or more permanents you control, cast it without paying its mana cost.

Spells you cast without trial have trial 1. (As you cast a spell with trial 1, an opponent of your choice may pay 1 life. If they don't, they fail the trial.) (As you cast this spell, an opponent of your choice may pay 1 life. If they don't, they fail the trial.)
Whenever an opponent fails a trial, you may discard a card. If you do, draw a card.

Whenever a creature you control dies, put a legacy counter on Testament to Heroism.
{T}: Add {C}.
{T}, Remove a legacy counter from Testament to Heroism: Add one mana of any color.

Enchant nonland permanent
Enchanted permanent's activated abilities can't be activated and triggered abilities of enchanted permanent don't trigger.

[+1]: The next card you foretell this turn costs {0} to foretell. You may discard a card. If you do, draw a card.
[–3]: Teufel deals 4 damage to any target and you gain 4 life.
[–6]: You get an emblem with “Whenever you cast a spell, you may pay life equal to the amount of mana spent to cast it. If you do, copy that spell and you may choose new targets for the copy.”

Thailen's Reprisal deals 2 damage to each of up to X targets.

First strike
Thailen, Heir to Daeland's power is equal to the number of other attacking or blocking creatures you control.

Thalassic Borough enters tapped unless you have 15 or less life.
{T}: Add {U} or {B}.

When Thallid Cultivator dies, mill four cards. Return a creature card milled this way to your hand.

Whenever you draw a card except for the first one you draw in each of your draw steps, each opponent loses 1 life.

Bulwark — When Tharanos' Legion enters, draw a card for each creature you control with toughness 4 or greater.

Flying
At the beginning of combat on your turn, gain control of up to one target creature an opponent controls. If you do, untap it, and it gets +4/+4 and gains flying and haste until end of turn. Sacrifice it at the beginning of the next end step.

Search your library for a card and put that card into your hand. Then shuffle.
When Tharyen's Machinations is engorged, you may search your library for a card with the same mana value as the permanent that engorged it, reveal it, put it into your hand, then shuffle.

Destroy target creature. Then if there are ten or more cards in your graveyard, return target creature card from your graveyard to your hand.

Flying, lifelink
Whenever you gain life, each opponent loses 1 life.
{4}{B}{B}: Create a 1/1 black Vampire creature token with lifelink for each nontoken creature that died this turn.

Indestructible
As long as your devotion to blue is less than five, Thassa isn't a creature.
At the beginning of each combat, you may tap or untap another target nonland permanent.
{2}{U}: Create a 1/1 blue Merfolk Rogue creature token with “{T}: Draw a card, then discard a card.”

Thawing Valley enters tapped unless you control a basic land.
{T}: Add {G} or {U}.

Your opponents play with their hands revealed.
Whenever you cast a spell with the same name as a card in an opponent's hand, draw two cards.

{T}: Add {C}.
{5}, {T}, Sacrifice The Aetherite Saloon: Each player discards their hand and draws seven cards.

Reconstruct {4}{B}{B}{B} (You may cast this from your graveyard for its reconstruct cost reduced by the mana value of a permanent you sacrifice as you cast it this way. Then exile this.)
Destroy all creatures. If The Afterlife Takes Its Due was reconstructed, create an X/X black Zombie Horror creature token, where X is the number of creature cards that have been put into graveyards this turn.

Once each turn, if a triggered ability of another legendary permanent you control would trigger, you may have it trigger an additional time.

At the beginning of the next end step, create X 1/1 white Spirit creature tokens with flying, where X is the number of creatures that died this turn.
Reconstruct {2}{W}{B} (You may cast this from your graveyard for its reconstruct cost reduced by the mana value of a permanent you sacrifice as you cast it this way. Then exile this.)