Aetheric Bauble

Uncover — {4}: Until end of turn, whenever you tap a land for mana, add {e}. Activate this ability only once per turn and only if you control seven or more basic lands.
{e}{e}: Add one mana of any color.
"A bauble of concentrated Aether could contain more power than anything we've created to date. I want every researcher on this!"
—Eshan Baat