Exquisite Blood

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

Bolas's Citadel

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.
{T}, Sacrifice ten nonland permanents: Each opponent loses 10 life.

Jumbo Cactuar

10,000 Needles — Whenever this creature attacks, it gets +9999/+0 until end of turn.