Dungeons 3

Done in the "The Gehenna Stones" level. For this trophy make a mental note of Thalya's health points and simply make sure her health never drops below 75%. While she is very powerful and you'll need her in the Overworld, she is particularly vulnerable in this level as she is paralysed while corrupting the Gehenna Stones, and must be protected by your minions as enemies spawn trying to stop you. As long as you have enough minions near her, the AI will always attack the nearest minion and not Thalya.

There are 4 Gehenna Stones to corrupt. Your 2nd Gehenna Stone (regardless of location) will spawn powerful bears. The 3rd will spawn waves of golems. Be prepared for either. The 4th one will be unlocked after the 1st 3 have been corrupted.