Blessing of Leeches

Flash
Enchant creature
At the beginning of your upkeep, you lose 1 life.
{0}: Regenerate enchanted creature.

Ring of Xathrid

{2}: Regenerate equipped creature. (The next time that creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)
At the beginning of your upkeep, put a +1/+1 counter on equipped creature if it's black.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Falthis, Shadowcat Familiar

Commanders you control have menace and deathtouch.
Partner (You can have two commanders if both have partner.)

Thrull Retainer

Enchant creature
Enchanted creature gets +1/+1.
Sacrifice Thrull Retainer: Regenerate enchanted creature.

Eternal Thirst

Enchant creature
Enchanted creature has lifelink and "Whenever a creature an opponent controls dies, put a +1/+1 counter on this creature." (Damage dealt by a creature with lifelink also causes its controller to gain that much life.)

Swamp

Strands of Undeath

Enchant creature
When Strands of Undeath enters, target player discards two cards.
{B}: Regenerate enchanted creature.