Knight's Fury is the spell used by holding and pressing either or when the Witch Points bar (the blue bar underneath Gretchen's health bar) is over half full. Heinrich transforms into a demonesque creature. Pressing will produce chainable standard attacks, will cause Heinrich to jump forwards and spin with his scythe attacking anything below or infront of him, will make Heinrich jump directly upwards and spin his scythe around him to damage all enemies in his vicinity. will dash forwards further than regular Heinrich can. Gretchen will disappear while in Knight's Fury and consequently none of her spells will be available though any already out will continue their effect. To earn the achievement, you need to defeat 200 enemies while in this mode. The easiest way to do this is to go on the easiest difficulty, Page, and start episode 3. The first group of enemies you encounter is seven Dendrites, which are very weak. Activate Knight's Fury and kill as many of the seven as you can. Once Knight's Fury finishes, press and choose to return to the episode select screen. The amount of kills will stay, and you can restart episode 3 for fast and easy kills. This technique will also work for Her True Strength.