msem-instigator

Trample, haste
When Tyrants of Bundan enters, tap all lands target player controls. They don't untap during their controller's next untap step.

Flying, vigilance
When Tyriel, Angelic Artisan enters, you may search your library for an Equipment card, reveal it, put it into your hand, then shuffle.
Whenever Tyriel attacks, you may put an Equipment card from your hand onto the battlefield, then attach it to Tyriel.

This spell costs {1} less to cast for each Scarecrow you control.
Other creatures you control get +0/+2 and have vigilance.

You may look at the top card of your library any time.
You may cast creature spells from the top of your library.
At the beginning of your end step, if Ulvenwald Howler didn't attack this turn, transform it.

Other Hounds you control have trample.
{R/W}, {T}: Put a +1/+1 counter on target Hound you control.

When Umbersteed dies, target creature an opponent controls gets -4/-4 until end of turn.
Foreshadow {5}{B}{B} (You may cast this spell for its foreshadow cost. If you do, also trigger its “dies” abilities when it enters.)

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

Resolute — Umbral Wolf can't be blocked by more than one creature as long as Umbral Wolf's power is greater than its base power.

Assault {X}{R}{R} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
Other Elementals you control get +1/+0.
When Unbound Annihilus assaults, create X 1/1 red Elemental creature tokens that are tapped and attacking.

Whenever you cast another creature spell, create a 1/1 green and white Elk Spirit creature token.
As long as you control five or more Elk, creatures you control get +3/+3 and have trample.

Hexproof
When Uncharted Leviathan enters, target creature can't be blocked this turn.

Enspirit (As you cast this spell, you may exile a nonenchantment creature you control until this leaves the battlefield or fails to resolve. Reduce this spell's cost by the exiled card's mana value.)
Deathtouch

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

This spell costs {1} less to cast for each Zombie creature card in your graveyard.
When Undead Harbinger enters, return target Zombie card from your graveyard to your hand.

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.

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

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.”

Flying, vigilance
When you attain Unfallen Angel, target opponent discards a card.

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

Add X mana in any combination of colors, where X is the amount of mana spent to cast Unravel Shattered Worlds.
Coalesce {7} (You may cast this from your graveyard for {7}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)

Unreflected Cultist can't be blocked by Reflections.

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

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.

Create a 2/2 white Angel creature token with flying.
Coalesce {6}{W}{W} (You may cast this from your graveyard for {6}{W}{W}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Flying