So last night I farmed normal Ledge until level 40 and blasted my way through Dominus (yes I have seen the true face of god...) into cruel. Managed to push to cruel Ledge and level to 45 before I went to bed.
Equipped a 5l chest and I currently have Arc > Faster Casting > Spell Echo > Chain > Mana Leech. I can literally sustain it infinitely providing I hit at least one mob. I'll replace the mana leech gem with something else when I can sustain the mana without it.
I also have Ball Lightning linked with Cast on Critical Strike, Lesser Multiple Projectiles (more orbs yeaaaaah) and added lightning damage to counter the damage loss from LMP. I guess my crit change is a bit low for now though because I haven't actually seen it proc yet. Hopefully when it does start to proc consistently it will be kind of ridiculous.
It occurred to me that I'm going to need a lightning res flask for ele reflect mobs or maps because I managed to one shot myself on the ele reflect mob in Imperial Gardens. In normal. Lesson learned...
Got two Cast when Damage Taken setups - one is level 1 linked to Molten Shell (L7 I think) and a quality enduring cry, supported by increased duration. The second is a higher level and is linked to Immortal Call and Elemental Weakness and is supported by increased duration too. The reason for this is because I'll have Molten Shell and Enduring Cry proc'd almost infinitely and when I start taking more damage Immortal Call will go off. It just helps me to get the most out of the endurance charges before they're consumed.
Toying with the idea of auras but not many actually affect Arc or Ball Lightning so it might be better to just leave them out until high level group play. I play with a group of IRL friends so we could co-ordinate which aura people run so there's no overlap.
Still destroying mobs and with Chain linked to Arc, even large packs of 10+ mobs are dropping like flies. Leveling pretty quickly, I think I'll keep farming cruel ledge until I get a couple more levels and then I'll push forward to docks to get to around 55, then it's off to merciless ledge.
I love this build already.