msem-instigator

Creatures you control dying cause abilities of that creature to trigger as though that creature entered the battlefield.
{2}{W}{B}, Sacrifice another creature: Destroy target nonland permanent.

At the beginning of your upkeep, exile the top card of your library. You may play it this turn. Whenever you cast an instant or sorcery spell exiled this way, you may copy it and you may choose new targets for the copy.

Flying
When Tyrant of Tributes enters the battlefield, target opponent sacrifices X permanents, where X is half the number of permanents they control, rounded up. You gain X life.

When you cast this spell, copy it for each Dragon permanent you control. You may choose new targets for the copies.
Tyrant's Breath deals 7 damage to target creature or planeswalker.

Flash
If a card or token would be put into an opponent's graveyard from anywhere, exile it instead.

When Unbound Expanse enters the battlefield, if an opponent controls more lands than you, create a Plains token. (It's a basic land with “{T}: Add {W}.”)
{1}{W}, Sacrifice Unbound Expanse: Exile each nonland permanent you control, then return those cards to the battlefield under your control.

Target opponent sacrifices half the permanents they control, rounded down.

Spend only mana produced by Treasures to cast spells.
{2}, Discard a card: Create two Treasure tokens.

Unceasing Flames deals X damage to any target, where X is 2 plus the number of cards named Unceasing Flames in your graveyard.
Conjure three cards named Unceasing Flames and shuffle them into your main library.

Whenever a creature you control is dealt damage, put a +1/+1 counter on that creature.

When Uncovered Mine enters the battlefield and at the beginning of your upkeep, return a random card from your graveyard to your hand.

When Uncovered Secrets enters the battlefield, search your library for an artifact card, reveal that card, then shuffle and put that card on top.
Concord — Creatures you control get +1/+1 as long as there are four or more card types among permanents you control.

When Undead Archivist enters the battlefield, return target instant or sorcery card from your graveyard to your hand.
Revive {5}{U} ({5}{U}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

When Undead Banneret enters the battlefield, if you control a legendary creature, each opponent loses 4 life.

Creature cards in your graveyard have revive {2}{B}{B}. ({2}{B}{B}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Concord — As long as there are four or more card types among permanents you control, you may cast the first spell you cast each turn without paying its mana cost.

Vigilance
Whenever Underpass Sentinel enters the battlefield or attacks, you may put a +1/+1 counter on another target creature you control without one.
Sacrifice Underpass Sentinel: Embattled creatures you control gain hexproof and indestructible until end of turn. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

When Undying Lich dies, create a 6/3 black Zombie Horror creature token with menace and “When this creature dies, create an 8/5 black Elder Demon Horror creature token with flying, deathtouch, and menace.”

When Undying Watcher enters the battlefield, germinate. (Put a +1/+1 counter on a creature or create a 1/1 green Saproling creature token.)
Sacrifice another creature: Undying Watcher gains indestructible until end of turn.

Return target creature card with mana value 3 or less from your graveyard to the battlefield.
Cycling {2} ({2}, Discard this card: Draw a card.)

Unearthed Legion's power and toughness are each equal to the number of cards in your graveyard.
At the beginning of your upkeep, mill a card.

Whenever a creature you control dies, you may return all cards that were inscribed onto that creature and all Auras that were attached to that creature to their owners' hands.

Create three 1/1 colorless Servo artifact creature tokens.
Exile Unending Armies. At the beginning of your upkeep, if you have more life than each opponent, you may cast it without paying its mana cost. Otherwise, put it into your graveyard.

Unending Slime enters the battlefield with X +1/+1 counters on it.
{2}{G}{G}{G}: Return Unending Slime from your graveyard to your hand.

Flying
When Unfettered Atrocity enters the battlefield, destroy target creature or planeswalker.