In combat, Owls typically use weapons that scale damage with Intellect, like the Wand and Gnarled Staff which allow the Owl to have range. Owls generally use runes that scale damage with Intellect, like Smite for stun, Magic Missile for damage and Consecrate for healing, etc. Owls, however, are not obligated to use these runes, as every rune offers its own functions, pros and cons and opportunities for better builds. You can consult the Advanced Guide to aid you in your rune and stat choice.
Owls generally fall into three categories:
Snipers, fragile but extremely high damage glass cannons.
Healers, powerful tanky supports that leave damage dealing to the melees on their team.