to all master here…
what affixes is the best for ORB skills? ( thunder element )
#respect_newbie 
Sorry, I had to do it 
But seriously: you can boost dmg of any skill simply by using a Topaz crystal and then rerolling the epic affix with Sapphire and Fluorite until you get +10 Orb.
The Reactor set would be fun. It provides your Orb with an arc-like effect thus allowing you to damage multiple enemies at once.
Living Force Set Affix makes your ORB more powerful and long duration
Doesn’t Orb damage 5 enemies already? Because when I get swarmed it procs 100% even if MH only has 11.8%.
reactor + living force(inc duration to 3sec and additional dmg at the half of duration when in return) then pump orb to lvl 20-40 depends on ur playstyle since at lvl 40 orb does not move forward nor backward only stay at 1 place(wer u spwn it)… (i prefer lvl20 more orb mobility though lvl40 is much stronger if use well)… if u plan using lvl20 orb then use other slot affix to add +10empower or +10amplify to inc ur orb dmg