msem-instigator

{2/B}: Umbral Stalker gains indestructible until end of turn. Tap it.

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

Whenever Unbudging Badger attacks, if its power is 4 or greater, it gains trample until end of turn.

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

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

When Undead Necromancer enters, search your library for a card, put that card into your graveyard, then shuffle.
As long as this card is in your graveyard, its name is Undead Servant.

When Undead Servant enters, create a 2/2 black Zombie creature token for each card named Undead Servant in your graveyard.

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Undercity Diplomat can't be blocked by marked creatures.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)

When this creature enters, search your library for a creature card with mana value 1 or less, reveal it, put it into your hand, then shuffle.
Arise {2}{W} ({2}{W}, Exile this from your graveyard as a sorcery: Create a black token copy of it that's also a Zombie and can't block.)

At the beginning of your upkeep, reveal the top card of your library. If it has the same name as a card in your graveyard, put the revealed card into your hand. Otherwise, put it into your graveyard.

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, 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.

Unfettered Noble can't be blocked unless defending player pays 3 life, discards a card, or sacrifices a nonland permanent for each creature they control that's blocking it.
Sacrifice a nonland permanent: Unfettered Noble gains indestructible until end of turn.

Ungoverned Sneak can't be blocked by creatures with greater power.
Attain {3}{U} ({3}{U}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Lifelink
Augmented — Whenever you cast a spell, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on United Guardian. It loses this ability and gains “Whenever United Guardian attacks, create two 1/1 blue Elemental creature tokens with flying that are tapped and attacking.”

Flying
Whenever you cast a spell from your graveyard, return Unliving Swarm from your graveyard to your hand.

When Unmasker of Fate's Design enters, look at target player's hand. Choose a nonland card from it and exile that card with a puzzle counter on it. As long as that card has a puzzle counter on it, that player may pay {2} and 1 life at any time. If they do, return the exiled card to their hand.

Unreflected Cultist can't be blocked by Reflections.

Trample
Whenever Unruly Cannoneer crews a Vehicle, that Vehicle gets +1/+1 and gains trample until end of turn.

Prowess
Whenever Unseen Hand attacks, exile target noncreature, nonland card with mana value 1 or less from your graveyard. Copy that card. You may cast the copy. (You still pay its costs.)

Glitch—Sacrifice a creature. (Remove one [restriction] for each time you pay the glitch cost.)
When Unshackled Revolutionary enters, you may destroy target creature an opponent controls [with mana value 3 or less]. [You lose 3 life.]

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Unstable Borer attacks each combat if able.

Menace
Unveil {3}{B}{R} ({3}{B}{R}: Transform this. Unveil only as a sorcery.)

Trample
Whenever Unstoppable Zealot deals damage to a player or noncreature permanent, you may put a land card from your hand or graveyard onto the battlefield.