I'm trying to merely survive in the 2nd Undead Forest using the trick I got from the Cluebook (run to the circle of stones and fight there) but the Treants overwhelm me (like they did in the first section before using the trick) and no amount of Blesses, Prayers and Aids seem to help. Does the teleporter from the first forest always place you in the same point fo the second? Any help would be appreciated. Thanks.

I saved up on all the fireball, ice and magic missile wands and brought a lot of big healing potions. The wands are usually enough to clear both levels of tree monsters. A haste spell would be useful to be able to use the wands faster.

If a character is close to dying, go into the inventory, place two big healing potions into it's hands, leave the inventory, quickly drink them and go back into the inventory.

Yes, the teleporter always goes to the same spot.

Stock up on fire spells/wands. Fireballs, Aganazer's Scorcher, and so on. Hopefully you brought enough mages.
Haste also does great for the ones that get too close, to quickly chop them up.

Keep in mind that you can run into the fog when overwhelmed, rest up and return, but also note that the trees will be there where you left them, so try to lure them away from the spot where you entered.