Hearthton, Holy City

Indestructible
{t}: Add three mana of any one color to your
mana pool.
Hearthton, Holy City, untaps during your
opponent's upkeep as well as yours.
During your opponent's combat phase and until
end of their turn, Hearthton, Holy City becomes
a 0/100 colorless wall creature that has reach and
can block any number of creatures.