Leeches

Target player loses all poison counters. Leeches deals that much damage to that player.

Platinum Angel

Flying
You can't lose the game and your opponents can't win the game.

Repay in Kind

Each player's life total becomes the lowest life total among all players.

Gideon of the Trials

+1: Until your next turn, prevent all damage target permanent would deal.
0: Until end of turn, Gideon of the Trials becomes a 4/4 Human Soldier creature with indestructible that's still a planeswalker. Prevent all damage that would be dealt to him this turn.
0: You get an emblem with "As long as you control a Gideon planeswalker, you can't lose the game and your opponents can't win the game."

Soul Echo

Soul Echo enters with X echo counters on it.
You don't lose the game for having 0 or less life.
At the beginning of your upkeep, sacrifice Soul Echo if there are no echo counters on it. Otherwise, target opponent may choose that for each 1 damage that would be dealt to you until your next upkeep, you remove an echo counter from Soul Echo instead.

Pristine Talisman

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.)

Death Cultist

Sacrifice Death Cultist: Target player loses 1 life and you gain 1 life.

Phyrexian Processor

As Phyrexian Processor enters, pay any amount of life.
{4}, {T}: Create an X/X black Phyrexian Minion creature token, where X is the life paid as Phyrexian Processor entered.

Angel's Grace

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
You can't lose the game this turn and your opponents can't win the game this turn. Until end of turn, damage that would reduce your life total to less than 1 reduces it to 1 instead.

Selenia, Dark Angel

Flying
Pay 2 life: Return Selenia, Dark Angel to its owner's hand.

Soul Conduit

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

Near-Death Experience

At the beginning of your upkeep, if you have exactly 1 life, you win the game.

Reverse the Sands

Redistribute any number of players' life totals. (Each of those players gets one life total back.)

Solemnity

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

Tainted Sigil

{T}, Sacrifice Tainted Sigil: You gain life equal to the total life lost by all players this turn. (Damage causes loss of life.)

Axis of Mortality

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