The Sunless Citadel

(Transforms from Whyte Manor Grounds.)
{t}: Add one mana of any color. When that mana
is spent to cast a creature spell, it enters the battlefield with an extra +1/+1 counter on it and
can't be countered.
At the beginning of each upkeep, if two or more
spells were cast last turn, transform The Sunless Citadel.