Lotus Petal

{T}, Sacrifice Lotus Petal: Add one mana of any color.

Dark Deal

Each player discards all the cards in their hand, then draws that many cards minus one.

Ad Nauseam

Reveal the top card of your library and put that card into your hand. You lose life equal to its mana value. You may repeat this process any number of times.

Swamp

Sickening Dreams

As an additional cost to cast this spell, discard X cards.
Sickening Dreams deals X damage to each creature and each player.

Maralen of the Mornsong

Players can't draw cards.
At the beginning of each player's draw step, that player loses 3 life, searches their library for a card, puts it into their hand, then shuffles.

Vampiric Tutor

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

Dark Sphere

{T}, Sacrifice Dark Sphere: The next time a source of your choice would deal damage to you this turn, prevent half that damage, rounded down.