msem-instigator

Create a 1/1 white Spirit creature token with flying. (Then exile this card. You may cast the artifact later from exile.)

At the beginning of each player's end step, that player chooses from among nonland permanents they control an artifact, a creature, an enchantment, and a planeswalker, then sacrifices the rest.

Deathtouch, lifelink
At the beginning of combat on your turn, for each creature your opponents control, you may tap an untapped creature you control. If you do, those creatures fight each other.

For each legendary permanent you control, this spell costs one mana of one of that permanent's colors less to cast. This effect reduces only the amount of colored mana you pay.
For each color, create a token that's a copy of a legendary permanent you control of that color, except the token isn't legendary.
Exile The Tale of Kings.

Creatures you control get +2/+0 until end of turn.
Metamorph {1}{W} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up and cast it at any time for its metamorph cost.)

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)

(As this Discovery enters and after your draw step, add a progress counter. Stop after you've discovered.)
I, II — Look at the top five cards of your library. Put up to one creature card with mana value 2 or less from among them onto the battlefield. Put the rest on the bottom of your library in a random order.
Discovery — At the beginning of combat on your turn, tap target creature an opponent controls.

{2}{R}: Thespian Soldier gains first strike until end of turn.

Flying
Whenever Theurgic Flock deals combat damage to a player, if it doesn't have a +1/+1 counter on it, put a +1/+1 counter on it.

When Third Legion Rider enters the battlefield, if you control an embattled creature, tap target creature an opponent controls. It doesn't untap during its controller's next untap step. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Primal {5}{R}{W} (During your turn, you may cast this spell for {5}{R}{W} instead of playing a land.)
Until end of turn, permanents you control gain indestructible and permanents you don't control lose indestructible. Then if if this spell was cast for its primal cost, destroy all nonland permanents.

When Thorn Tender enters the battlefield, rouse 1, then put a +1/+1 counter on each creature you control. (Put a +1/+1 counter on a permanent you control. If it isn't a creature, tap it and it becomes a 0/0 creature in addition to its other types.)

(Choose only one work as a sorcery to add its ability.)
When Those Lost to the Waves enters the battlefield, search your library for an artifact card with mana value 3 or less, reveal it, put it into your hand, then shuffle.
{1}{W}: Fight the Current
Equipped creatures you control get +1/+1.
{3}{U}: Soul of the Sea
At the beginning of combat on your turn, you may have target noncreature artifact become a 3/3 artifact creature until end of turn.

Flash
When Threadspinner enters the battlefield, untap each enchanted permanent you control. Enchanted creatures you control get +1/+1 until end of turn.

Each creature you control enters the battlefield with an additional +1/+1 counter on it.
Each planeswalker you control enters the battlefield with an additional loyalty counter on it.

Exile any number of target creatures and/or planeswalkers you control. You gain 1 life for each card exiled this way, then return them to the battlefield under your control.

The next creature spell you cast this turn may be cast as though it had flash and costs {1} less to cast. If it entering the battlefield causes a triggered ability of it to trigger, that ability triggers an additional time.

Each player sacrifices a creature with mana value X or greater.
Return up to one target creature card with mana value X or less from your graveyard to the battlefield.

Augmented — When you cast this spell, if it's your turn and you've spent {W}{U}{B}{R}{G} to cast spells this turn, copy it twice. You may choose new targets for the copies.
Thunder Road deals 3 damage to any target. You gain 3 life.

Target creature gets +1/+1 for each creature you control and gains flying and vigilance until end of turn.

Whenever Thundering Towershell attacks, return a creature card with mana value 5 or less from a graveyard to the battlefield under your control. Trigger a death knell of that creature.

Flash
Whenever Thundermane Fox enters the battlefield or attacks, target creature you control gains double strike until end of turn.

Creature tokens you control get +1/+1.
Whenever Thyra, Winter's Warden enters the battlefield or attacks, you may pay {1}{G/W}. If you do, create Bruga, a legendary 2/2 green and white Wolf creature token.

Whenever Tide Crasher attacks, if you control another Merfolk, tap target creature defending player controls.

Permanents you control gain indestructible until end of turn. Untap each creature you control.
Cycling {W} ({W}, Discard this card: Draw a card.)