Knights Contract

After Straeggele transforms into her *Beast* form the first part of the fight is to just simply run away from her towards the bottom of the screen. Its pretty easy , just avoid the red spiked pillars as they will slow you down. Once you enter the court yard and begin the main fight with her, try and concentrate your attacks on one single leg if possible. Use Gretchen's spike spell when given the chance to anchor the leg to the ground and attack it. The B button will appear for the finisher (tho i never activated it). After enough damage has been done to her she will jump away onto the surrounding buildings and shoot down fire breath which is really easy to avoid. Use this time to carry Gretchen and heal you both if needed. After the fire breath Straeggele will jump back down (avoid if possible) and you can start your attack again. After enough damage has been done the QTE will start and once completed the fight will be over. The QTE buttons (in my game at least) were as follows. A button - LS side to side - A button - Left stick UP - Rapidly press Y.
If I have missed anything or if voted negative please let me know so this guide can be fixed. Thank You

Straeggele is the end boss of the 2nd chapter. She takes the form of a giant three legged muscular crocodile-ish monster with many eyes and a giant foot for a hind leg. After doing a lot of damage you will have to pass a QTE to win. Once completing the QTE, you will get the achievement.

This is a tip for the rather difficult QTEs wich have a small time window to press the appropriate button.
First of all the Guide button is needed because you can't interrupt the QTEs with a regular press on the Start button.
Then you should have a list of the button presses for the QTEs for the boss you are fighting for.
Then when the QTE sequence starts, hit the Guide button and memorize the first button you need to press. Hit the Guide button again and press Start to continue the sequence, wait for the prompt and hit the appropriated button. Now press the Guide button again and memorize the next button prompt needed. Hit Guide again and Start to continue the sequence and so on. This makes the QTEs an absolute breeze which takes much of the difficulty away.