Isniri, Serenity of the Frey

Flying, Hexproof
When Isniri, Serenity of the Frey enters the
battlefield, put 1 knowledge counter on Isniri
in the beginning of your upkeep. you gain life
equal to knowledge counter in your end step.
every time Isniri deals combat damage towards
put a +1 experience counter on her. sacrifice
experience tokens and take one creature from your
graveyard equivalent to its mana cost.