Stash of Reagents

Whenever you cast an instant or sorcery spell,
put a charge counter on Stash of Reagents.
{t}, Remove a charge counter from Stash of
Reagents: Add one mana of any color. Spend this
mana only to cast instant or sorcery spells.
{2}, {t}, Sacrifice Stash of Reagents: You may cast
an instant or sorcery spell from your hand
without paying its mana cost.