There's a lovely E/Mo build in this sites archive stuffs. Essentially, its like this.
Stone Daggers
Obsidian Flame
Crystal Wave
Armor of Earth
Kinetic Armor
Aura of Restoration
Earth Attunement
Balthazars Spirit
Cast balthazar's spirit right when you enter the map, its an enchantment that stays with you at all times, taking away one regen, so getting it up asap means you can go right into battle with full energy.
Right before battle, cast Earth Attunement, armor of earth, kinetic armor, and aura of restoration(make sure the attunement is up before the armor buffs, gives you more energy).
In order to make this build work, you NEED stone daggers. Kinetic armor gives you some 70+ armor for 8 seconds, and the time is reset if you cast a spell. Stone daggers allows you to keep it up.
Now, with all your buffs up(watch them, Armor of Earth dies after 30 seconds, relatively quickly, and you don't want to go too long without the attunement) you shouldn't take much damage at all. And each time you're attacked, you get energy(via balthazars).
I've tested this build, and it does work, and if you read the article of the original creator, it says it works better with more hydra. And it does. I fought 9 hydra at the same time, because thats as much as i could aggro and still keep kinetic up. Killing the first hydras was easy, I hardly lost any health(it was noticeable, but I healed so quickly that it really didn't cause any problem).
Keeping up your enchantments, you also need to deal out damage. While you CAN kill 9 hydra with stone daggers...I would not advise such a plan of action. Rather, use crystal wave as soon as it recharges. It'll attack all hydras, and by the time you've killed 8 hydras, the last is on its last legs(metaphorically).
And while Obsidian Flame is a good spell, doing 100 or so dmg and ignoring armor, it does cause exhaustion, and I wouldn't recommend spamming it too much. I found that healthy substitutes for this skill include:
Earthquake-also causes exhaustion, but does AoE dmg
Aftershock-you won't get the second set of damage, but it does a healthy load as it is, and it's to all the hydras that are attacking you melee style, just like crystal wave.
Just so you know. I killed the 9 hydras with level 12 earth magic, level 12 energy storage. I'm waiting to use a sup earth rune on my first piece of geomancer armor(im getting all 4 15k sets) and so I had lvl 12 earth magic(no earth helm, saving money for 15k armor)
However, attribute wise, I would think that having level 16 earth(sup rune + helm) and level 15 energy storage(sup rune) would make this build immensly more easy to work with. Just so you know, at level 15, Aura of Restoration gives exactly %400 energy cost of your spells to your hp. if you use stone daggers, you're healed 20 hp.
As for weapons, same thing. I didn't have earthy wands or artifacts, so I used my fire things. As you might guess, my fiery weapons didn't help earth spells one bit, but it worked for me all the same. In short, though, it doesn't matter what you have for a weapon/artifact, it will work.
Yeah this build is nice, I switched the obsidian flame from obsidian flesh so I'm not knockdown anymore and can easily round up 11 hydra's and survive then too wipe them all out, you feel mighty good afterwards
