Exquisite Blood

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

Eriette of the Charmed Apple

Each creature that's enchanted by an Aura you control can't attack you or planeswalkers you control.
At the beginning of your end step, each opponent loses X life and you gain X life, where X is the number of Auras you control.

Sphere of Safety

Creatures can't attack you or planeswalkers you control unless their controller pays {X} for each of those creatures, where X is the number of enchantments you control.

Sanguine Bond

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