Urza, Lord High Artificer

When Urza enters, create a 0/0 colorless Construct artifact creature token with "This token gets +1/+1 for each artifact you control."
Tap an untapped artifact you control: Add {U}.
{5}: Shuffle your library, then exile the top card. Until end of turn, you may play that card without paying its mana cost.

Thassa's Oracle

When this creature enters, look at the top X cards of your library, where X is your devotion to blue. Put up to one of them on top of your library and the rest on the bottom of your library in a random order. If X is greater than or equal to the number of cards in your library, you win the game. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

Urza's Saga

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — This Saga gains "{T}: Add {C}."
II — This Saga gains "{2}, {T}: Create a 0/0 colorless Construct artifact creature token with 'This token gets +1/+1 for each artifact you control.'"
III — Search your library for an artifact card with mana cost {0} or {1}, put it onto the battlefield, then shuffle.

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Emrakul, the Aeons Torn

This spell can't be countered.
When you cast this spell, take an extra turn after this one.
Flying, protection from spells that are one or more colors, annihilator 6
When Emrakul is put into a graveyard from anywhere, its owner shuffles their graveyard into their library.

Umbral Mantle

Equipped creature has "{3}, {Q}: This creature gets +2/+2 until end of turn." ({Q} is the untap symbol.)
Equip {0}

Lotus Petal

{T}, Sacrifice this artifact: Add one mana of any color.

Enter the Infinite

Draw cards equal to the number of cards in your library, then put a card from your hand on top of your library. You have no maximum hand size until your next turn.

Training Grounds

Activated abilities of creatures you control cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Ponder

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

Omen Hawker

{T}: Add {C}{U}. Spend this mana only to activate abilities.

Island

Ancient Tomb

{T}: Add {C}{C}. This land deals 2 damage to you.

Ulamog, the Ceaseless Hunger

When you cast this spell, exile two target permanents.
Indestructible
Whenever Ulamog attacks, defending player exiles the top twenty cards of their library.

Brainstorm

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

City of Traitors

When you play another land, sacrifice this land.
{T}: Add {C}{C}.

Emrakul, the Promised End

This spell costs {1} less to cast for each card type among cards in your graveyard.
When you cast this spell, you gain control of target opponent during that player's next turn. After that turn, that player takes an extra turn.
Flying, trample, protection from instants

Blightsteel Colossus

Trample, infect, indestructible
If Blightsteel Colossus would be put into a graveyard from anywhere, reveal Blightsteel Colossus and shuffle it into its owner's library instead.

Wasteland

{T}: Add {C}.
{T}, Sacrifice this land: Destroy target nonbasic land.

Street Wraith

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
Cycling—Pay 2 life. (Pay 2 life, Discard this card: Draw a card.)