Anyone used this mythic skill on their MH weapon? Haven’t see anyone post items using it. Rockblast, CosmicOrb, Barrage are the most common one. I want to know if Arc is cool to use.
depend on build, well i will craft that on my Aphrodite dagger when i have time to make 1 mythic dagger and abandon eternal obsidian dagger. The motive is to put debuff on enemy before u launch your actual attack.
is that for 2V2? if not, i dont see the use of Arc’s 'beams of energy chain off of enemies, hitting up to 5 targets. BTW, does “chain off” means like not letting them attack or a series of attack?
For me, it’s better to use Reactor with orb proc (or change your special to orb). Works well on PVE. It’s total chaos with all the orbs flying. 
This way you can have another mythic on your MH.
how about orb special+cosmicorb?
Well they can still attack, arc can be used for multi stacking purpose for example shock when u attack and arc happen to proc, ignore the damage it deal but focus on how much attack it hit per sec. let say it hit 4 times sec so basically u already have your enemy under shock debuff at max (+50% damage receive) so when u actual attack like blinkstrike will deal extra 50% damage.