Growth Stones

Conjure {5} (whenever this enters the battlefield, you may pay {5}, if you do this enters the battlefield as an artifact.)
{t}: add {g} to your mana pool. This cant be used to cast noncreature spells.
If this was conjured, it gains ({t}: add {g}{g}{g} to your mana pool. If you cast a creature card using this mana, draw a card.)