Knights Contract

I got this achievement on Episode 13: Witch's Enclosure II. On this stage you will be controlling Gretchen. If you already passed this part of the game, it can be chosen from the chapter select menu.

Before starting, make sure that your Mag Mell's Rose spell is upgraded to level three. By this point in the game you should have lots of points to spend on upgrades.

Go through the first stage, and then the second stage in the city. There's a tricky part in a sewer where you'll be chased by a knight who can kill you in one hit, but if you use the trap spell on him you can get away.

After about 15 minutes, you'll be back in the strange dimension again. Just after Gretchen makes the 'Is this just a game to you?" comment, you'll be attacked by three black knights in a small area. Move around until they're all close together, and use Mag Mell's Rose on them. Fully upgraded this spell will grab all three enemies and do lots of damage to them. More importantly, it will unlock the achievement.

Note: you may even get this achievement earlier during this stage, since there are parts in the city where you'll get attacked by multiple tough enemies and if you use Mag Mell's Rose you can get lots of hits on them.

By combining the Colchis Trap (The Venus Flytrap spell,preferably on lvl 2) and Tannhauser's Illusion (spell that creates afterimages of Heinrich's scythe to increase number of hits) you can get this achievement by fighting the Gold Wight near the top of the stairs on your way to Rupunzel on episode 11