Biorhythm

Each player's life total becomes the number of creatures they control.

Belbe, Corrupted Observer

At the beginning of each postcombat main phase, the active player adds {C}{C} for each of your opponents who lost life this turn. (Damage causes loss of life.)

Aurora of Emrakul

Flying, deathtouch
Whenever this creature attacks, each opponent loses 3 life.

Cryptolith Fragment

This artifact enters tapped.
{T}: Add one mana of any color. Each player loses 1 life.
At the beginning of your upkeep, if each player has 10 or less life, transform this artifact.

Cryptolith Fragment // Aurora of Emrakul

Obscuring Haze

If you control a commander, you may cast this spell without paying its mana cost.
Prevent all damage that would be dealt this turn by creatures your opponents control.

Bladegriff Prototype

Flying
Whenever this creature deals combat damage to a player, destroy target nonland permanent of that player's choice that one of your opponents controls.

Woodland Bellower

When this creature enters, you may search your library for a nonlegendary green creature card with mana value 3 or less, put it onto the battlefield, then shuffle.