Sanguine Bond

Whenever you gain life, target opponent loses that much life.

Sythis, Harvest's Hand

Whenever you cast an enchantment spell, you gain 1 life and draw a card.

Solemnity

Players can't get counters.
Counters can't be put on artifacts, creatures, enchantments, or lands.

Sanctum Weaver

{T}: Add X mana of any one color, where X is the number of enchantments you control.

Enchantress's Presence

Whenever you cast an enchantment spell, draw a card.

Exquisite Blood

Whenever an opponent loses life, you gain that much life.

Phyrexian Unlife

You don't lose the game for having 0 or less life.
As long as you have 0 or less life, all damage is dealt to you as though its source had infect. (Damage is dealt to you in the form of poison counters.)