In my first playthrough I could kill most ennemies without engaging combat.

My wizard has oil patch (not sure of the name - one of the 1st earth spells) and a fireball.

I could cast the patch, then burn it.
I was far away anough that the ennemies did not see my character and so they did not engage the fight.

I missed the xp but it eased the battle.
When the goul was low life I engaged the battle to finish him off and get some xp.

(It was my 1st playthrough and as I missed lower level quests my team was too low level to fight the goul so I had to resort to this tactic).

Imarion