In Hero 30 the mission before the last you'll meet a girl named Sasha. Do the following to get the achievement.
1.Talk to her in the first village across the first bridge, she has green hair, and she'll run away.
2. Head north to another bridge and protect her from monsters.
3. She'll want to give you a tour so head back to where you met her first and speak to her again.
4.Head north back to the bridge she'll show you where the evil lord is.
5.Head to that castle and fight the evil lord. Afterwards head to village at the bottom of the hill this castle was on.
6.Now head north to the monument, it looks like a stone tablet, north of the village
7.Head south of where you first defended her into the forest, here there is a clearing where Sasha is waiting for you.
8.Go back to the monument up north and smash it.
9.Head back to the first village you met Sasha in. Everyone is a zombie now, kill all but the rightmost zombie. Use the flee commands just enough to not fight the last zombie. After a few seconds of this dialog will pop up and you will let the zombie live.
[DO NOT HAVE DUEL GRIEVES EQUIPPED OR YOU CANNOT RUN AWAY]
10.Go kill the real evil lord (might want to do a time reset its a long fight) and you'll earn the achievement.