Priest of Gix

When Priest of Gix enters, add {B}{B}{B}.

Culling the Weak

As an additional cost to cast this spell, sacrifice a creature.
Add {B}{B}{B}{B}.

Flying
When Kokusho, the Evening Star dies, each opponent loses 5 life. You gain life equal to the life lost this way.

Until end of turn, whenever a player taps a Swamp for mana, that player adds an additional {B}.

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

{2}, {T}: Add {B} for each Swamp you control.

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