This trophy is obtained for completion of the seventh main story mission and is thus an unmissable part of the progression through the game.
**Minor Mission Spoilers Follow**
Upon finishing the previous mission, you will be directed to report in to the Adventurer's Guild. There you will get a quest to help Lucain with some rune stones. At Lucain's, he will give you an 'S' rune stone and direct you to the Forgotten Sanctuary to fight a golem. Once there, you will meet a monk who will give you a holy tablet to purify the Sanctuary. Eventually you will reach a bridge-like environment with two huge golem statues. Proceed forward past the rightmost one and note the 'L' and 'F' runes carved onto the pillar. Click (L1 or R3) on these two runes and then the 'S' in the pack (it will show up directly below your character as soon as you start a runeword). Order does not matter - this will cast the 'Life From Stone' rune spell and activate the golem.
The golem will slowly walk forward while demons will attack it from both sides. Protect the him and he will eventually reach the evil golem and start to fight it. Your job here is to continue keep the golem alive until it kills the evil golem. Pay careful mind to the goblins with bombs, these will do significant damage to your golem. The enemy golem has a strong hit that will inflict great damage (which may one-shot you) so make sure to stay far enough back to avoid this fate. Eventually the golem falls and you replace the evil tablet with the holy one.
The Trophy will not award until you return to Lucain's Tower to show him the evil tablet you took from the Sanctuary.