Reach

Ulvenwald Hydra's power and toughness are each equal to the number of lands you control.

When Ulvenwald Hydra enters, you may search your library for a land card, put it onto the battlefield tapped, then shuffle.

Whenever a creature you control with toughness 4 or greater dies, draw a card.

: Regenerate Ulvenwald Primordials.

At the beginning of each upkeep, if a player cast two or more spells last turn, transform Ulvenwald Primordials.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Flying

Whenever Umara Raptor or another Ally you control enters, you may put a +1/+1 counter on Umara Raptor.

Auras attached to permanents you control have umbra armor. (If an enchanted permanent you control would be destroyed, instead remove all damage from it and destroy an Aura attached to it.)

Umbris, Fear Manifest gets +1/+1 for each card your opponents own in exile.

Whenever Umbris or another Nightmare or Horror you control enters, target opponent exiles cards from the top of their library until they exile a land card.

When Unassuming Sage enters, you may pay . If you do, create a Sorcerer Role token attached to it. (Enchanted creature gets +1/+1 and has "Whenever this creature attacks, scry 1.")

: Add . Spend this mana only to pay a disturb cost or cast an instant or sorcery spell.

Protection from white (This creature can't be blocked, targeted, dealt damage, enchanted, or equipped by anything white.)

Unchained Berserker gets +2/+0 as long as it's attacking.

Other blue creatures you control have "Whenever this creature becomes tapped, draw a card, then discard a card."

Other artifact creatures you control get +1/+1.

: Until end of turn, target creature you control becomes a blue artifact in addition to its other colors and types. Activate only as a sorcery. ( can be paid with either or 2 life.)

If a Zombie you control would deal combat damage to a player, instead that player mills that many cards.

Whenever a creature card is put into an opponent's graveyard from their library, exile that card and create a 2/2 black Zombie creature token.

When Undead Butler enters, mill three cards. (Put the top three cards of your library into your graveyard.)

When Undead Butler dies, you may exile it. When you do, return target creature card from your graveyard to your hand.

, Discard a card: Return Undead Gladiator from your graveyard to your hand. Activate only during your upkeep.

Cycling (, Discard this card: Draw a card.)

, : Exile target Skeleton, Vampire, or Zombie.

Zombie spells you cast cost less to cast.

Zombie creatures you control get +2/+1.

When Undercity Eliminator enters, you may sacrifice an artifact or creature. When you do, exile target creature an opponent controls.

, Sacrifice another creature: Put a +1/+1 counter on Undercity Necrolisk. It gains menace until end of turn. Activate only as a sorcery. (It can't be blocked except by two or more creatures.)

: Create a Treasure token. Activate only if a creature died this turn. (It's an artifact with ", Sacrifice this artifact: Add one mana of any color.")

Renown 1 (When this creature deals combat damage to a player, if it isn't renowned, put a +1/+1 counter on it and it becomes renowned.)

: Regenerate Undercity Troll. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Whenever Undercover Crocodelf deals combat damage to a player, investigate. (Create a Clue token. It's an artifact with ", Sacrifice this artifact: Draw a card.")

Disguise (You may cast this card face down for as a 2/2 creature with ward . Turn it face up any time for its disguise cost.)

Deathtouch

Menace (This creature can't be blocked except by two or more creatures.)

When Underdark Explorer enters, you take the initiative.

Undergrowth Scavenger enters with a number of +1/+1 counters on it equal to the number of creature cards in all graveyards.

If you would draw a card, instead look at the top three cards of your library, then put one into your hand and the rest into your graveyard.

Pay 4 life: Underrealm Lich gains indestructible until end of turn. Tap it.

, , Discard a card: Return target creature card from your graveyard to your hand.

Underworld Charger can't block.

Escape—, Exile three other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)

Underworld Charger escapes with two +1/+1 counters on it.

When Underworld Hermit enters, create a number of 1/1 green Squirrel creature tokens equal to your devotion to black. (Each in the mana costs of permanents you control counts toward your devotion to black.)

Whenever Underworld Sentinel attacks, exile target creature card from your graveyard.

When Underworld Sentinel dies, put all cards exiled with it onto the battlefield.

Flying

Sphinx spells you cast cost less to cast.

Whenever Unesh, Criosphinx Sovereign or another Sphinx you control enters, reveal the top four cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

Unhallowed Cathar can't block.

At the beginning of your end step, you lose 1 life.

Unimpeded Trespasser can't be blocked.

Changeling (This card is every creature type.)

When Unlucky Witness dies, exile the top two cards of your library. Until your next end step, you may play one of those cards.

Defender

: Unruly Catapult deals 1 damage to each opponent.

Whenever you cast an instant or sorcery spell, untap Unruly Catapult.

Whenever another creature you control dies, put a +1/+1 counter on Unruly Mob.

When Unscrupulous Contractor enters, you may sacrifice a creature. When you do, target player draws two cards and loses 2 life.

Plot (You may pay and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Changeling (This card is every creature type.)

Whenever you or a permanent you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays .

When Unshakable Tail enters and at the beginning of your upkeep, surveil 1.

Whenever one or more creature cards are put into your graveyard from your library, investigate. (Create a Clue token. It's an artifact with ", Sacrifice this artifact: Draw a card.")

, Sacrifice a Clue: Return Unshakable Tail from your graveyard to your hand.

Whenever another creature enters, Unstable Shapeshifter becomes a copy of that creature, except it has this ability.

When Unstoppable Ogre enters, target creature can't block this turn.

Kicker (You may pay an additional as you cast this spell.)

Vigilance, trample

If Untamed Kavu was kicked, it enters with three +1/+1 counters on it.

Vigilance

Embalm (, Exile this card from your graveyard: Create a token that's a copy of it, except it's a white Zombie Human Warrior with no mana cost. Embalm only as a sorcery.)

Vigilance

Eerie — Whenever an enchantment you control enters and whenever you fully unlock a Room, put a possession counter on Unwilling Vessel.

When Unwilling Vessel dies, create an X/X blue Spirit creature token with flying, where X is the number of counters on Unwilling Vessel.

Flying

: Unyaro Bees gets +1/+1 until end of turn.

, Sacrifice Unyaro Bees: It deals 2 damage to any target.

Disguise (You may cast this card face down for as a 2/2 creature with ward . Turn it face up any time for its disguise cost.)

When Unyielding Gatekeeper is turned face up, exile another target nonland permanent. If you controlled it, return it to the battlefield tapped. Otherwise, its controller creates a 2/2 white and blue Detective creature token.

Flying

First strike

Whenever you cast an instant or sorcery spell, Urabrask deals 1 damage to target opponent. Add .

: Exile Urabrask, then return it to the battlefield transformed under its owner's control. Activate only as a sorcery and only if you've cast three or more instant and/or sorcery spells this turn.