Kariss, Loaner of Pain

Whenever you pay life as part of a cost or effect, you create a tapped Pain Debt token
where X is the amount of life spent.
(It's an artifact with " {2}, {t}, Sacrifice this artifact: You deal X damage to any target,
and gain X life.") .
{w/b}, Pay 3 life: Kariss phases out until the next upkeep.