Skyshroud Cutter

If you control a Forest, rather than pay this spell's mana cost, you may have each other player gain 5 life.

Axis of Mortality

At the beginning of your upkeep, you may have two target players exchange life totals.

Plague Drone

Flying
Rot Fly — If an opponent would gain life, that player loses that much life instead.

Kavu Predator

Trample
Whenever an opponent gains life, put that many +1/+1 counters on Kavu Predator.

Punishing Fire

Punishing Fire deals 2 damage to any target.
Whenever an opponent gains life, you may pay {R}. If you do, return Punishing Fire from your graveyard to your hand.

Grove of the Burnwillows

{T}: Add {C}.
{T}: Add {R} or {G}. Each opponent gains 1 life.

Refreshing Rain

If an opponent controls a Swamp and you control a Forest, you may cast this spell without paying its mana cost.
Target player gains 6 life.

Tainted Remedy

If an opponent would gain life, that player loses that much life instead.

Invigorate

If you control a Forest, rather than pay this spell's mana cost, you may have an opponent gain 3 life.
Target creature gets +4/+4 until end of turn.

Soul Conduit

{6}, {T}: Two target players exchange life totals.

Reverent Silence

If you control a Forest, rather than pay this spell's mana cost, you may have each other player gain 6 life.
Destroy all enchantments.

Needlebite Trap

If an opponent gained life this turn, you may pay {B} rather than pay this spell's mana cost.
Target player loses 5 life and you gain 5 life.

Vizkopa Guildmage

{1}{W}{B}: Target creature gains lifelink until end of turn.
{1}{W}{B}: Whenever you gain life this turn, each opponent loses that much life.

False Cure

Until end of turn, whenever a player gains life, that player loses 2 life for each 1 life they gained.

Rain of Gore

If a spell or ability would cause its controller to gain life, that player loses that much life instead.

Mirror Universe

{T}, Sacrifice Mirror Universe: Exchange life totals with target opponent. Activate only during your upkeep.

Wall of Shards

Defender, flying
Cumulative upkeep—An opponent gains 1 life. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)