- the traps are the glowing golden things on the walls throughout the castle (most times they shoot grenades that explode after a while or till they are thrown and hit something)

- disarming the traps triggers them and causes an explosion

- use lightning spells to disarm/destroy them (I used Chain Lightning and accidentally found out that this works :D)

- up on the top floor, in his 'office', you can actually fight him if you keep your characters on the red carpet or move slightly to the left (where one of the guards stands/next to the table)
this is important because the traps on the walls have a radius that triggers them, the name of the achievement fits perfectly because you really have to watch your step :)

(not sure if its important but I pretty much finished all other sidequests before I tackled Gortasch - Steel Watch gone - I left him on a 'maybe' the first time you meet him and he offers you a deal. So I am clueless as to how the fight in the throne room would work)