Darksteel Citadel

Steam Vents

({T}: Add {U} or {R}.)
As Steam Vents enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

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.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Proteus Staff

{2}{U}, {T}: Put target creature on the bottom of its owner's library. That creature's controller reveals cards from the top of their library until they reveal a creature card. The player puts that card onto the battlefield and the rest on the bottom of their library in any order. Activate only as a sorcery.

Negate

Stern Scolding

Counter target creature spell with power or toughness 2 or less.

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

Island

Remand

Counter target spell. If that spell is countered this way, put it into its owner's hand instead of into that player's graveyard.
Draw a card.

Spreading Seas

Enchant land
When Spreading Seas enters the battlefield, draw a card.
Enchanted land is an Island.

Flayer Husk

Living weapon (When this Equipment enters the battlefield, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +1/+1.
Equip {2}

Fblthp, the Lost

When Fblthp, the Lost enters the battlefield, draw a card. If it entered from your library or was cast from your library, draw two cards instead.
When Fblthp becomes the target of a spell, shuffle Fblthp into its owner's library.

Tormod's Crypt

{T}, Sacrifice Tormod's Crypt: Exile target player's graveyard.

Fact or Fiction

Reveal the top five cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

Otawara, Soaring City

{T}: Add {U}.
Channel — {3}{U}, Discard Otawara, Soaring City: Return target artifact, creature, enchantment, or planeswalker to its owner's hand. This ability costs {1} less to activate for each legendary creature you control.

Goblin Charbelcher

{3}, {T}: Reveal cards from the top of your library until you reveal a land card. Goblin Charbelcher deals damage equal to the number of nonland cards revealed this way to any target. If the revealed land card was a Mountain, Goblin Charbelcher deals double that damage instead. Put the revealed cards on the bottom of your library in any order.

Batterbone

Living weapon (When this Equipment enters the battlefield, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +1/+1 and has vigilance and lifelink.
Equip {5}

Day's Undoing

Each player shuffles their hand and graveyard into their library, then draws seven cards. If it's your turn, end the turn. (Exile all spells and abilities from the stack, including this card. Discard down to your maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Mishra's Bauble

{T}, Sacrifice Mishra's Bauble: Look at the top card of target player's library. Draw a card at the beginning of the next turn's upkeep.

Narcolepsy

Enchant creature
At the beginning of each upkeep, if enchanted creature is untapped, tap it.

Force of Negation

If it's not your turn, you may exile a blue card from your hand rather than pay this spell's mana cost.
Counter target noncreature spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Thoughtcast

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Draw two cards.

Dress Down

Flash
When Dress Down enters the battlefield, draw a card.
Creatures lose all abilities.
At the beginning of the end step, sacrifice Dress Down.