Doomsday

Search your library and graveyard for five cards and exile the rest. Put the chosen cards on top of your library in any order. You lose half your life, rounded up.

Shadow of Mortality

If your life total is less than your starting life total, this spell costs {X} less to cast, where X is the difference.

The Cauldron of Eternity

This spell costs {2} less to cast for each creature card in your graveyard.
Whenever a creature you control dies, put it on the bottom of its owner's library.
{2}{B}, {T}, Pay 2 life: Return target creature card from your graveyard to the battlefield. Activate only as a sorcery.

Blinkmoth Infusion

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Untap all artifacts.

Laboratory Maniac

If you would draw a card while your library has no cards in it, you win the game instead.

Kaboom!

Choose any number of target players or planeswalkers. For each of them, reveal cards from the top of your library until you reveal a nonland card, Kaboom! deals damage equal to that card's mana value to that player or planeswalker, then you put the revealed cards on the bottom of your library in any order.

Nekusar, the Mindrazer

At the beginning of each player's draw step, that player draws an additional card.
Whenever an opponent draws a card, Nekusar deals 1 damage to that player.

Draco

Domain — This spell costs {2} less to cast for each basic land type among lands you control.
Flying
Domain — At the beginning of your upkeep, sacrifice this creature unless you pay {10}. This cost is reduced by {2} for each basic land type among lands you control.