disi: Here what I did:
When the fight starts, I name the tentacles from the left 1,2,3,4. All tentacles go up and you need to evade if they come down (usually close to where you stand).

You need to use the 'Yrden' sign.

Go where 2 comes down, this is also where you get the trap indicated, either place the Kayran trap or a Yrden sign trap. If you place the Kayran trap, immediately run away because it blows very quickly.
If you use the Yrden sign, stand next to your trap to lure the tentacle to come down on you and evade in the last moment. Once the arm is trapped, cut it off with the sword.

Go to tentacle 1 and place another Yrden sign, wait for the arm to come down, evade and cut it off.

Do the same with 3.

An event starts and you have to click left or right mouse button to grab 4 and ride on it. In mid-air you have to fast-click left or right mouse button to cut it off. Then I think the space-bar to release close to the ground.

Run onto the remains of the temple to the left and then up the ramp, not sure if there is anything more to click here or the end-scene started immediately.

Don't worry, I died at least 20 times here :)