Ah so suddenly your thorns build that you were so eagerly spamming in the comment section before does not help you out at all so far into the game? What a surprise!
If you want to get past that area you either need to kill everything in one turn which is difficult without a bit of good luck or have both moderate damage output, plus moderate defense output. I would recommend you stack on armor pieces and aim specifically for the archangel armor and the paladin's plate because one adds +2 haste and the other gives you 8 armor which makes a difference since early on enemies can not hurt you at all, but once you arrive at the Magma Core it effectively reduces enemy damage by 1/3.
For Snakes and bats, you will either need a cleansing rag + heartstone gem combo or a My First Wand to counter the poison.
When it comes down to what type of weapon you should use, aim for a bow, a wand, cleavers, shivs or accessories that increase your damage output.
The Ring Of Doom is very potent in that department, and, with the assumption that you have a considerable amount of mana stones, you can dish out over 30 damage per hit easily which should kill anything under 3 turns. Spend money at a shop to buy one if you can.