Keyword: Threshold

Creatures you control get +0/+2 until end of turn.
Threshold — If seven or more cards are in your graveyard, choose a color. Creatures you control also gain protection from the chosen color until end of turn.

Return target creature card from your graveyard to your hand.
Threshold — Return that card from your graveyard to the battlefield instead if seven or more cards are in your graveyard.

Flying
Threshold — Other creatures you control get +2/+2 as long as seven or more cards are in your graveyard.

Lightning Surge deals 4 damage to any target.
Threshold — If seven or more cards are in your graveyard, instead Lightning Surge deals 6 damage to that permanent or player and the damage can’t be prevented.
Flashback (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Flying
Threshold — As long as seven or more cards are in your graveyard, Fledgling Dragon gets +3/+3 and has “: Fledgling Dragon gets +1/+0 until end of turn.”

Flying
Whenever Treacherous Vampire attacks or blocks, sacrifice it unless you exile a card from your graveyard.
Threshold — As long as seven or more cards are in your graveyard, Treacherous Vampire gets +2/+2 and has “When Treacherous Vampire dies, you lose 6 life.”

Target nonblack creature gets -1/-1 until end of turn.
Threshold — If seven or more cards are in your graveyard, instead destroy that creature. It can’t be regenerated.

Flash
Threshold — As long as seven or more cards are in your graveyard, Teroh’s Vanguard has “When Teroh’s Vanguard enters the battlefield, creatures you control gain protection from black until end of turn.”

: Untap target land.
Threshold — : Untap up to three target lands. Activate this ability only if seven or more cards are in your graveyard.

First strike
Threshold — As long as seven or more cards are in your graveyard, Possessed Barbarian gets +1/+1, is black, and has “, : Destroy target red creature.”

Discard a card: Putrid Imp gains flying until end of turn.
Threshold — As long as seven or more cards are in your graveyard, Putrid Imp gets +1/+1 and can’t block.

Vigilance
Threshold — As long as seven or more cards are in your graveyard, Possessed Nomad gets +1/+1, is black, and has “, : Destroy target white creature.”

Destroy target land.
Threshold — If seven or more cards are in your graveyard, instead destroy that land and Rancid Earth deals 1 damage to each creature and each player.

Kamahl’s Sledge deals 4 damage to target creature.
Threshold — If seven or more cards are in your graveyard, instead Kamahl’s Sledge deals 4 damage to that creature and 4 damage to that creature’s controller.

Haste
Threshold — As long as seven or more cards are in your graveyard, Centaur Chieftain has “When Centaur Chieftain enters the battlefield, creatures you control get +1/+1 and gain trample until end of turn.”

Flying
Threshold — As long as seven or more cards are in your graveyard, Gloomdrifter has “When Gloomdrifter enters the battlefield, nonblack creatures get -2/-2 until end of turn.”

Threshold — As long as seven or more cards are in your graveyard, Pardic Arsonist has “When Pardic Arsonist enters the battlefield, it deals 3 damage to any target.”

, : Target creature gets -1/-1 until end of turn.
Threshold — , : Target creature gets -2/-2 until end of turn. Activate this ability only if seven or more cards are in your graveyard.

Trample
Threshold — As long as seven or more cards are in your graveyard, Possessed Centaur gets +1/+1, is black, and has “, : Destroy target green creature.”

Flying
Threshold — As long as seven or more cards are in your graveyard, Boneshard Slasher gets +2/+2 and has “When Boneshard Slasher becomes the target of a spell or ability, sacrifice it.”

Flying
Threshold — As long as seven or more cards are in your graveyard, Possessed Aven gets +1/+1, is black, and has “, : Destroy target blue creature.”

Flying
Threshold — As long as seven or more cards are in your graveyard, Mystic Familiar gets +1/+1 and has protection from black.

Destroy all enchantments.
Threshold — If seven or more cards are in your graveyard, instead destroy all enchantments, then return all cards in your graveyard destroyed this way to the battlefield.

Add .
Threshold — Add instead if seven or more cards are in your graveyard.

Protection from black
Threshold — Nantuko Blightcutter gets +1/+1 for each black permanent your opponents control as long as seven or more cards are in your graveyard.