msem-instigator

Gain control of target nonland permanent if you control a permanent with a greater mana value. Otherwise, destroy that permanent.

Choose one —
• Creatures you control become colorless Forest lands until end of turn. (They have “{T}: Add {G}” and lose all other types and abilities.)
• Lands you control become 2/2 green creatures in addition to their other types and gain haste until end of turn.

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 its coalesce cost. If you do, put it onto the battlefield as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)

Choose one, then choose another for each card named Unraveling in your graveyard.
• Counter up to one target spell.
• Scry 2, then draw a card.
• Up to three target lands your opponents control don't untap during their controller's next untap step.
• Creatures your opponents control get -4/-0 until end of turn.

Choose one, then choose another for each card named Unrelenting in your graveyard.
• Creatures get -1/-1 until end of turn.
• Create a 2/2 blue Elemental creature token.
• Each opponent loses 3 life and you gain 3 life.
• Search your library for a card with mana value 4 or greater, reveal it, put it into your hand, then shuffle.

Trample, ward {1}
Whenever you gain life, put a +1/+1 counter on Unrelenting Noble.
{1}, Sacrifice a permanent: You gain 2 life.

This spell costs {2} less to cast if your starting deck contained at least forty cards more than the minimum deck size.
When Unrivaled Fireweaver enters the battlefield, you may exile a red instant or sorcery card you own from outside the game. Until the end of your next turn, you may play that card.

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.)

Discard a card: Unseen Maniac gets +1/+1 and can't be blocked this turn.
Whenever Unseen Maniac deals combat damage to a player, draw a card.

You may have Unstable Impersonator enter the battlefield as a copy of any creature on the battlefield chosen at random.

Vanishing 5 (This permanent enters the battlefield with five time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
{1}{R}, Remove a time counter from Unstable Magmaling: Flip a coin. If you win the flip, it deals 3 damage to any target.

Unstoppable Slaughter deals 1 damage to each creature and each player. Whenever a creature dealt damage by Unstoppable Slaughter this turn dies this turn, repeat that process.

Choose one, then choose another for each card named Unsuspecting in your graveyard.
• You may return a permanent you control to its owner's hand.
• You may put an artifact, creature, or land card with mana value 2 or less from your hand onto the battlefield.
• Untap up to three target permanents.
• You gain 4 life.

Whenever a land becomes tapped, its controller sacrifices it and creates a Treasure token.

Whenever you cast a nongreen spell, creatures you control get +1/+1 until end of turn.
Wanderlust — When Untethered Disciple enters the battlefield, if you control four or more differently named lands, create two 1/1 Scout creature tokens that are all colors.

{T}: Add {C}.
{T}, Sacrifice Untethered Spire: Choose target land card in your graveyard that was put there from the battlefield this turn. Return that card to your hand.

For each land you control, you may return a land card from your graveyard to the battlefield tapped.

Untrekked Territory enters the battlefield tapped.
{T}: Add {B} or {G}.
When Untrekked Territory enters the battlefield, you may put a loyalty counter on a planeswalker you control.

When Unwavering Sentinel enters the battlefield, for each creature you control, create a white Aura enchantment token named Shield with “Enchant creature” and “If enchanted creature would be destroyed, instead remove all damage from it and sacrifice this Aura” attached to that creature.

Ward {1}
Other Scouts you control get +1/+1.
Whenever three or more Scouts you control attack, draw a card.

Unzari Ruins enters the battlefield tapped.
{T}: Add {C}.
Tap five untapped creatures you control: Unzari Ruins becomes a 10/10 Construct artifact creature with trample until end of turn. It's still a land.

All creatures have “When this creature enters the battlefield, destroy target creature with a lesser mana value.”

Constructs you control have haste.
When Urak, Voice of the Horde or another Construct enters the battlefield under your control, creatures you control get +1/+0 until end of turn.
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

When Urn of Heroes enters the battlefield, you may search your library for a legendary card, put that card into your graveyard, then shuffle.
{T}: Add {C}.

You may have Urushi, the Ripple in the Smoke enter the battlefield as a copy of any creature on the battlefield, except it's an enchantment. (It's not a creature.)