Cha, The Stargazer

Constellation —Whenever Cha, The Stargazer or
another enchantment enters the battlefield under
your control, exile target nonenchantment
permanent. Return that card to the battlefield
under its owner's control at the beginning of the
next end step.
Whenever a permanent enters the battlefield
from exile, add {g} or {w}. Until the beginning of
your next end step, you don't lose this mana as
steps and phases end.