Undercity Sewers

({T}: Add {U} or {B}.)
Undercity Sewers enters tapped.
When Undercity Sewers enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Entomb

Search your library for a card, put that card into your graveyard, then shuffle.

Forbidden Orchard

{T}: Add one mana of any color.
Whenever you tap Forbidden Orchard for mana, target opponent creates a 1/1 colorless Spirit creature token.

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Swamp

Island

Pact of Negation

Counter target spell.
At the beginning of your next upkeep, pay {3}{U}{U}. If you don't, you lose the game.

Force of Will

You may pay 1 life and exile a blue card from your hand rather than pay this spell's mana cost.
Counter target spell.

Slaughter Pact

Destroy target nonblack creature.
At the beginning of your next upkeep, pay {2}{B}. If you don't, you lose the game.

Atraxa, Grand Unifier

Flying, vigilance, deathtouch, lifelink
When Atraxa, Grand Unifier enters, reveal the top ten cards of your library. For each card type, you may put a card of that type from among the revealed cards into your hand. Put the rest on the bottom of your library in a random order. (Artifact, battle, creature, enchantment, instant, land, planeswalker, and sorcery are card types.)

Phage the Untouchable

When Phage the Untouchable enters, if you didn't cast it from your hand, you lose the game.
Whenever Phage deals combat damage to a creature, destroy that creature. It can't be regenerated.
Whenever Phage deals combat damage to a player, that player loses the game.

Sudden Substitution

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Exchange control of target noncreature spell and target creature. Then the spell's controller may choose new targets for it.

Leveler

When Leveler enters, exile all cards from your library.

Polluted Delta

{T}, Pay 1 life, Sacrifice Polluted Delta: Search your library for an Island or Swamp card, put it onto the battlefield, then shuffle.

Ancient Tomb

{T}: Add {C}{C}. Ancient Tomb deals 2 damage to you.

Personal Tutor

Search your library for a sorcery card, reveal it, then shuffle and put that card on top.

Underground Sea

Show and Tell

Each player may put an artifact, creature, enchantment, or land card from their hand onto the battlefield.

Archon of Cruelty

Flying
Whenever Archon of Cruelty enters or attacks, target opponent sacrifices a creature or planeswalker of their choice, discards a card, and loses 3 life. You draw a card and gain 3 life.

Stifle

Counter target activated or triggered ability. (Mana abilities can't be targeted.)

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.

Careful Study

Ponder

Look at the top three cards of your library, then put them back in any order. You may shuffle.
Draw a card.