Sinkhole

Mox Jet

Dark Ritual

Weakness

Enchant creature
Enchanted creature gets -2/-1.

Black Lotus

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

Swamp

Unholy Strength

Enchant creature
Enchanted creature gets +2/+1.

Paralyze

Enchant creature
When Paralyze enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.
At the beginning of the upkeep of enchanted creature's controller, that player may pay {4}. If the player does, untap the creature.

Drudge Skeletons

{B}: Regenerate Drudge Skeletons. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Demonic Tutor

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

Black Knight

First strike (This creature deals combat damage before creatures without first strike.)
Protection from white (This creature can't be blocked, targeted, dealt damage, or enchanted by anything white.)

Hypnotic Specter

Flying
Whenever Hypnotic Specter deals damage to an opponent, that player discards a card at random.