Previously, you wanted to wrap up the gnome chase quest and hit level 3 in the sycamore tree area, but with the last round of patches you can do the temple at level 2 now safely to hit 3 with. Either way, Trolls are very challenging and should indeed be tackled by level 3 or higher parties, but they ARE killable even at level 2 if you get a little lucky have have a way to finish them off (deal acid or fire damage once they are down and still targettable - it means they are regenerating, but even one point of acid from a flask will finish them off).