POB : https://pastebin.com/rerAAj3Z
Maven : https://youtu.be/F2F60Ac_bwA

I've played Arc with Triumvirate ring in this league, and it was quite decent.Total budget was 20~25ex iirc. It should be much cheaper now.You can change the helm for Arc chain enchanted one. -10% dps, but much cheaper and better for mapping.Killing end game bosses was quite easy actually. I could kill Feared with this setup.

Spell Echo vs Unleash

I've used Spell Echo before (with Algor Mortis gloves), but I ended up with Unleash (with Doedre's gloves). DPS got lowered bit, but actual DPS against end game bosses is much better imo. And I felt it's much safer. I wonder why they deleted seal gaining speed from passive tree tho..

Triumvirate Ring

1. 30% less soul cost - More Vaal arc buff uptime, thus more single target dmg for Arc. And of course, I can use more Vaal arc while mapping. I love this ring.
2. 150% more damage for Vaal arc - EZ 50% shock. EZ off screen clearing.
3. You can take whatever you want for the 3rd mod. I choose Tailwind.

Storm brand

1. Onslaught support - to get 20% cast speed against bosses, 20% ms for mapping.
2. Culling support - +10% overall dps
3. Faster Casting support - for smoothness, better chance to get Onslaught, little DPS boost for Storm Brand itself.
4. Storm Brand deals about 10%~12% DPS of my Arc. Not much, but it helps.