Pianist's Familiar

Bestow {2}{u} (If you cast this card for its
bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
Enchanted creature has cumulative upkeep {1}. (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.)