Lotus Petal

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

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.

Swamp

Dark Ritual

Sickening Dreams

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

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.

Varragoth, Bloodsky Sire

Deathtouch
Boast — {1}{B}: Target player searches their library for a card, then shuffles and puts that card on top. (Activate only if this creature attacked this turn and only once each turn.)

Feldon's Cane

{T}, Exile Feldon's Cane: Shuffle your graveyard into your library.

Shrouded Lore

Target opponent chooses a card in your graveyard. You may pay {B}. If you do, repeat this process except that opponent can't choose a card already chosen for Shrouded Lore. Then put the last chosen card into your hand.

Glacial Chasm

Cumulative upkeep—Pay 2 life. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
When Glacial Chasm enters the battlefield, sacrifice a land.
Creatures you control can't attack.
Prevent all damage that would be dealt to you.

Boseiju, Who Shelters All

Boseiju, Who Shelters All enters the battlefield tapped.
{T}, Pay 2 life: Add {C}. If that mana is spent on an instant or sorcery spell, that spell can't be countered.