First of all, Rat Cave shouldn't be that hard. When I was testing the game, I completed it over 10 times without losing a single fight. You can find a Sling (ranged weapon) for Elowen and a Shovel (2H melee weapon) for the main character right after entering Rat Cave, after which you can pretty much one-hit kill rats.
Elowen's Ranged Accuracy is 65% in the beginning, but you can get it to about 80% during this first version (and 100% later, making her a sharpshooter). With the Double Shot skill, which Elowen learns at level 3, she can shoot 2 stones instead of one with her slingshot, and it is very likely that at least one of the stones hits the target.
The chance of a melee attack hitting depends on the opponent's Dodge skill, so it is often advisable to attack the opponent with the lowest Dodge first. For example, the Goblin Archers have significantly lower Dodge than the Goblin melees. You can check the opponents' Dodge as well as other stats in the tooltip (on the Android version, you can see the tooltip by pressing and holding on the opponent). If you equip your main character with a shield, it is often a good strategy to stun the opponent first with Shield Bash, because stunned characters cannot attack or dodge any melee attack. ;)
