Jotun Owl Keeper

Cumulative upkeep {w} or {u} (At the beginning
of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)

When Jötun Owl Keeper is put into a graveyard from play, put a 1/1 white Bird creature token with flying into play for each
age counter on it.