Flames of Vengeance is indeed a very great part !!! So great and addictive I almost darf not to start playing that part afraid I will forget I live in Belgium and not in Aleroth city
With the Dragon Terror Patrol, try this :
after the video, on the moment they start to attack ... jump/run fast behind on of the towers (I always choose the tower most close by the teleporter platform) and if you have still the Amulet of the North with you you can use Hide in Shadows* or find another yewellery item with this skill on or invest at least 1 point
After this (you're now behind the tower and with Hide in Shadows used the chance the enemies followed you is almost nihil !) you can first make a seperate save game !
Then I always summon my Creature and the Summon Ghost**
A Creature with a Ghoulish Head (Rush Attack & Fatality) I find really helpful !
I use Priest skills like Charm, Blind & Fear ... really powerfull skills if you know how to make best use of them
* but know that if you going to use this skill NO arrow or spell is going to strike you while you "use" this skill ( so just before the Hide in Shadow spell is started to work you're still visible !)
** a fantastic helpful Ghost who can heal you and shoot fireballs, but know that it is important to upgrate Summon Ghost to the highest level you can because then the Ghost is a higher level, stronger and also can heal you a lot more (HP point) in one time !!