Pillars of Mist

{t}: Add {c} to your mana pool. Put a Mist counter on Pillars of Mist.
So long as there are 3 or more Mist counters
on Pillars of Mist, It's a portal in addition to
it's other types.(A portal is a land that has {t}: Add one purple mana.)
Mysteries lie within the mist, but you can't see
them.