There is a good reason for wanting to use the northern entrance, but it'll be a real test your Might & Magic skills to pull it off at a low level.
Of course you'll want to have used all the resources of Alvar -- the Wells, the Pedestal and the Temple. You'll want to cast Bless and Fire Aura before entering also.
At a low level you might not have hardened your body armor. You'll need that in order to take some of the hits you'll receive without having your Armor broken. Without Expert level Alchemy you would have had to have found or purchased the Harden Item Potion.
You'll also find certain Spells to be very useful, though for most of these you will have to rely on their Scrolls. Mass Fear is especially helpful, and you'll only really need it once. You can get a similar result using Charm on many targets. Also noteworthy are Inferno and Berserk. Be very careful using Spells like Fireball and Dragon Breath in this confined space.
Finally, make sure to have a lot of Potion Bottles on hand. You'll be able to use Wasp Wings to make more potent Potions from your weak Reagents, though it'd be nice to save some for later.