Buried under a thin layer of dirt, it was known for centuries as Mount Sardia.

Colossus of Sardia

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Colossus of Sardia doesn't untap during your untap step.
{9}: Untap Colossus of Sardia. Activate only during your upkeep.

The List

Masters Edition IV

Trample (If this creature would deal enough damage to its blockers to destroy them, you may have it deal the rest of its damage to defending player or planeswalker.)
Colossus of Sardia doesn't untap during your untap step.
{9}: Untap Colossus of Sardia. Activate this ability only during your upkeep.

Tenth Edition

Trample
Colossus of Sardia doesn't untap during your untap step.
{9}: Untap Colossus of Sardia. Play this ability only during your upkeep.

From the Sardian mountains wakes ancient doom: / Warrior born from a rocky womb.

Fifth Edition

Trample
Colossus of Sardia does not untap during your untap phase.
o9: Untap Colossus of Sardia. Use this ability only during your upkeep.

The ability that untaps it during your upkeep has been returned to an activated ability. There is no restriction on how many times it can be untapped during your upkeep with this ability.