My suggest earth mage build is tight on skill points in the game

Earth: moderate damage, moderate cool down, high sp cost per skill, damage reduces from 3 or more avalon aron mobs. Unlike wind skills can't chain continuously.

I recommend dagger skills in between waiting time. Earth skills are all one hit skills except gold dragon.

From lv41 to lv80: Just as wind, I reconsidered about earth mastery expert, and think it is worthwhile to get easier access than elemental master. My suggest earth mage build is tight on skill points.

lv41-44 - Sonic dagger, Assassin Dagger.

lv45 - Twin Dragon 2

lv46 - 49 - Stone armor

lv50 - Twin dragon 3

lv51 - Stone armor

lv52 - 57 - Dagger Mastery basic/earth mastery expert

lv59, 60 - save that point from 59 to get gold dragon at 60

lv64, 65 - gold dragon 2

lv69, 70 - gold dragon 3

Not that many points left in between those levels: I recommend max out stone armor reduce 20 damage per physical hit helps a lot. Non supportive pot type just follows above.

Resting type add total of at least 5 points to Mind Square before or between dagger skill and stone armor.

Self Healing type adds 2 points to Undine Heal low, mid and high. Then work on dagger skills and stone armor.