For the mages...

Now this is the elemental list the game gives for which type of elements work best against others...

fire vs wind
wind vs fire
earth vs water
water vs earth

Although these do work, you may find some other combo's work aswell..such as water vs fire. Mages have three elements Fire, wind and earth, and priests have water element attacks. You may notice later down the road some mages using certain attacks like Earth Spikes not as a high damaging aoe but to slow the mobs from hitting the tank as often. That helps priests heal and saves the endurance on gear

If you are not sure of what element the monster is you need to look infront of it's name where the circle is...it will have a color-
green=earth
white=wind
red=fire
blue=water

no circle means no element so anything goes.

Oh small note, if you are soloing with a mage fire thorn is good, but in a party it's not so good. when you are near a mob it will pull the aggro away from the tank and they will all attack you.

Feel free to add/comment or ask anything to this posty