I am having a bit of trouble killing this guy, why is it important to get the monks first - they just seem to stand around not doing much.

As soon as you kill 'Letec he respawns in one of the remaining monks.
Actually this could be a challenge. - Has anyone tried to kill Aec'Letec without killing the monks in their human state? hmmmm...

Thanks for the tip - I will keep trying (damn those pesky monks!!)

<font color="cyan">I killed him by killing him twice(one of the monks in monster form)</font>

Ha, I finally killed him. I don't know obout you but it was a bit of an anticlimax to TotSC! You don't even get to see him die properly.