Look at the top four cards of your library. You may reveal up to two instant and/or sorcery cards from among them and put the revealed cards into your hand. Put the rest on the bottom of your library in any order.

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)

When Unctus's Retrofitter enters, up to one target artifact you control becomes an artifact creature with base power and toughness 4/4 for as long as Unctus's Retrofitter remains on the battlefield.

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.)

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

Trample, haste

You may cast Undead Sprinter from your graveyard if a non-Zombie creature died this turn. If you do, Undead Sprinter enters with a +1/+1 counter on it.

Manifest dread. (Look at the top two cards of your library. Put one onto the battlefield face down as a 2/2 creature and the other into your graveyard. Turn it face up any time for its mana cost if it's a creature card.)

You may return a permanent card from your graveyard to your hand.

When Undercellar Sweep enters, you take the initiative.

Whenever you attack, if you or a player you're attacking has the initiative, you create two 1/1 white Soldier creature tokens that are tapped and attacking.

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.)

Target opponent discards a card. Then they may discard an additional card. If they don't, conjure a duplicate of a random card from their library into your hand. It perpetually gains "You may spend mana as though it were mana of any color to cast this spell."

: 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.")

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)

: Undercity Shade gets +1/+1 until end of turn.

Undergrowth — Distribute X +1/+1 counters among any number of target creatures you control, where X is the number of creature cards in your graveyard as you cast this spell. Creatures you control gain vigilance until end of turn.

Target opponent sacrifices a creature of their choice. If you control a creature with power 4 or greater, you gain 4 life.

Whenever Undercover Butler attacks the player with the most life or tied for most life, it can't be blocked this turn.

You may have Undercover Operative enter as a copy of any creature on the battlefield, except it enters with a shield counter on it if you control that creature. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)

CARDNAME enters the battlefield with ten eyestalk counters on it.

If CARDNAME would be dealt damage, remove that many eyestalk counters from it instead. If you can't, sacrifice it.

Whenever CARDNAME attacks, reveal cards from the top of your library until you reveal an instant, sorcery, or enchantment card with converted mana cost less than the number of eyestalk counters on CARDNAME. You may cast it without paying its mana cost. Shuffle your library.

: Add .

, , Exile Underdark Rift: Roll a d10. Put target artifact, creature, or planeswalker into its owner's library just beneath the top X cards of that library, where X is the result. Activate only as a sorcery.

(: Add or .)

Underground Mortuary enters tapped.

When Underground Mortuary enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

(: Add or .)

If damage would be dealt to Undergrowth Champion while it has a +1/+1 counter on it, prevent that damage and remove a +1/+1 counter from Undergrowth Champion.

Landfall — Whenever a land you control enters, put a +1/+1 counter on Undergrowth Champion.

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

Whenever an artifact you control enters, you may pay . If you do, each opponent loses 1 life and you gain 1 life.

, Sacrifice Underhanded Designs: Destroy target creature. Activate only if you control two or more artifacts.

Vigilance

When Undermountain Adventurer enters, you take the initiative.

: Add . If you've completed a dungeon, add six instead.

Flash (You may cast this spell any time you could cast an instant.)

Undersea Invader enters tapped.

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

When you unlock this door, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Underworld Cerberus can't be blocked except by three or more creatures.

Cards in graveyards can't be the targets of spells or abilities.

When Underworld Cerberus dies, exile it and each player returns all creature cards from their graveyard to their hand.

Constellation — Whenever Underworld Coinsmith or another enchantment you control enters, you gain 1 life.

, Pay 1 life: Each opponent loses 1 life.

Whenever an opponent draws a card, Underworld Dreams deals 1 damage to that player.

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.

Enchant creature

Enchanted creature gets +2/+2 and can't block.

When Undying Rage is put into a graveyard from the battlefield, return Undying Rage to its owner's hand.

Up to three target creatures can't block this turn.

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.

Shuffle your library, then reveal the top card. If it's a nonland card, you may cast it without paying its mana cost. If it's a land card, you may put it onto the battlefield and return Unexpected Results to its owner's hand.

Devoid (This card has no color.)

Draw three cards and create a 0/1 colorless Eldrazi Spawn creature token with "Sacrifice this creature: Add ."

Destroy target Equipment. If that Equipment was attached to a creature, Unforge deals 2 damage to that creature.

Spree (Choose one or more additional costs.)

+ — Destroy target creature.

+ — Create a 1/1 red Mercenary creature token with ": Target creature you control gets +1/+0 until end of turn. Activate only as a sorcery."

, Pay 1 life: Draw a card, then discard a card.

Unhallowed Cathar can't block.

: Add .

, : Put target Zombie card from your graveyard on top of your library.

Enchant creature

When enchanted creature dies, return that card to the battlefield under your control with a +1/+1 counter on it.

Flying

When Unidentified Hovership enters, exile up to one target creature with toughness 5 or less.

When Unidentified Hovership leaves the battlefield, the exiled card's owner manifests dread.

Crew 1

Exile target attacking creature if its power is less than or equal to the number of Soldiers on the battlefield.

Unimpeded Trespasser can't be blocked.

2 — : Add one mana of any color.

3 — Whenever this creature attacks, if it's not a Brushwagg, it gets +X/+0 until end of turn, where X is the number of supertypes, card types, and subtypes it has.

2 — 5/1

4 — 4/8

Changeling (This card is every creature type.)

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for .)

Draw X cards.