Thunderhoof Kirin

Haste, Vigilance
When Thunderhoof Kirin enters the battlefield
or attacks, it deals 1 damage to any target.
At the beginning of each opponent's end step,
that player may have Thunderhoof Kirin deal
damage to target player other than you with
more life than them equal to the total amount of
life lost this turn among all players. This damage
can't be prevented.