How to destroy a LOOK pedal as it won't come off anyway I've tried everything, from brute force, WD40 overnight, heat from a gas torch (trying not to damage the carbon crank itself), to using an extended arm for extra force.

Nothing will remove this darn pedal! The 8mm hex hole is now slipping so there is no more grip. Even the alloy wrench started to bend!

Ok, here is the low down.

Colnago C40 frame with Campagnolo Record Ultra Torque carbon cranks. Left pedal comes off easy, but the right drive pedal is fooked! Both pedals are LOOK Classics. Both were put on 2 years ago with grease, so they should have been easy to unwind. I suspect I annoyed someone on the bunch races and he went over and over tightened the pedal in vengeance! Bastard! I have an idea who it was too!

Anyway, the question is - how do I kill it!?

I am thinking nice clean fine metal blade on a hack-saw, cut pedal off, then drill middle outwards and hopefully it will unscrew itself without unscrewing the thread attached to the crank!

Any other suggestions?

Thanks
Heating the pedal is not going to help here.  Cool the pedal might.  But if the hex is stripped too late.  

Use penetrating oil like Liquid Wrench over WD40 for this. 
I would have soaked it two days in penetrating oil before I went brute force.
The risk of brute force is you that you strip out the crank. 

Use a drill press as it is really hard to center by hand. 
If you get the bit big enough it will fracture the pedal axle.
But you don't want the bit big enough to scar the crank.

I would see if you can get the pedal part of the pedal off and have enough of the axle to grab on to with a pipe wrench.  Soak it for 2 days in penetrating oil before you go at it with a pipe wrench.