The Imperial City

The Imperial City enters the battlefield tapped.
{t}: Add one mana of any color to your mana
pool. If that mana is used to cast a legendary
creature spell, you may put a +1/+1 counter on
that creature.
"I am your emperor, Uriel Septim. By the grace
of the Gods, I serve Tamriel as her ruler."
~ Uriel Septim VII