If you would pay life while your library has at least that many cards in it, exile that many cards from the top of your library instead.

+1: Look at the top two cards of your library. Exile one of them and put the other into your hand.

-2: Create two 1/1 black Nightmare creature tokens with "At the beginning of combat on your turn, if a card was put into exile this turn, put a +1/+1 counter on this creature."

-7: Target player exiles the top X cards of their library, where X is the total mana value of cards you own in exile.

Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

No more than two creatures can attack you each combat.

Destroy all creatures. They can't be regenerated.

Destroy all creatures. They can't be regenerated. Draw a card for each creature destroyed this way.

Cycling {3}{B}{B} ({3}{B}{B}, Discard this card: Draw a card.)

When you cycle Decree of Pain, all creatures get -2/-2 until end of turn.

Search your library for a card, put that card into your hand, then shuffle.

Creatures with power greater than the number of cards in your hand can't attack.

Geralf's Messenger enters the battlefield tapped.

When Geralf's Messenger enters the battlefield, target opponent loses 2 life.

Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Search your library for a card, put that card into your hand, then shuffle. You lose 3 life.

({B/P} can be paid with either {B} or 2 life.)

Lifelink

For each {B} in a cost, you may pay 2 life rather than pay that mana.

Whenever you cast a black spell, put a +1/+1 counter on K'rrik, Son of Yawgmoth.

Activated abilities of artifacts your opponents control can't be activated.

+1: Until your next turn, up to one target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value.

-2: You may reveal an artifact card you own from outside the game or choose a face-up artifact card you own in exile. Put that card into your hand.

+1: Target player discards a card.

-2: Search your library for a card, then shuffle and put that card on top.

-8: Put all creature cards from all graveyards onto the battlefield under your control.

+1: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.

-3: Target creature gets +X/+X or -X/-X until end of turn, where X is the number of Swamps you control.

-6: You get an emblem with "Swamps you control have '{T}: Add {B}{B}{B}{B}.'"

+1: Each player discards a card.

-2: Target player sacrifices a creature.

-6: Separate all permanents target player controls into two piles. That player sacrifices all permanents in the pile of their choice.

Enchant planeswalker

Enchanted planeswalker has "[-8]: Put all creature cards from all graveyards onto the battlefield under your control."

Whenever a creature deals damage to enchanted planeswalker, destroy that creature.

+1: Create a 2/2 black Zombie creature token. Mill two cards.

-3: Return target creature card from your graveyard to the battlefield. That creature is a black Zombie in addition to its other colors and types.

-7: Destroy all non-Zombie creatures.

Whenever a creature you control dies, draw a card.

+1: Create a 2/2 black Zombie creature token.

-4: Each player sacrifices two creatures.

-9: Each opponent chooses a permanent they control of each permanent type and sacrifices the rest.

Lifelink

Whenever another nontoken creature you control dies, exile Liliana, Heretical Healer, then return her to the battlefield transformed under her owner's control. If you do, create a 2/2 black Zombie creature token.

+2: Each player discards a card.

-X: Return target nonlegendary creature card with mana value X from your graveyard to the battlefield.

-8: You get an emblem with "Whenever a creature dies, return it to the battlefield under your control at the beginning of the next end step."

Skip your draw step.

Whenever you discard a card, exile that card from your graveyard.

Pay 1 life: Exile the top card of your library face down. Put that card into your hand at the beginning of your next end step.

At the beginning of your end step, if you didn't activate a loyalty ability of a planeswalker this turn, you lose 2 life.

{4}, {T}: For each planeswalker you control, you may activate one of its loyalty abilities once this turn as though none of its loyalty abilities have been activated this turn.

As an additional cost to cast this spell, pay X life.

All creatures get -X/-X until end of turn.

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

Protection from Humans

Pay 1 life, Sacrifice another creature: Put a -1/-1 counter on up to one target creature and draw a card.

{B}{B}, Discard a card: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)