I wanted to pick a league starter that is a really smooth mapper and can at least do the (non-uber) pinnacle bosses + the feared.

Arc doesn't have nearly the damage of other ignite skills like WoC or Vaal FB but to me, it has the smoothest playstyle.

With the new reworked Singularity and Thunderfist you can get some very decent Vaal Arc dps for bosses. In fact, socketing arc in thunderfist is better than 6 linking it. If they're cheap you could even attempt to corrupt for +2 duration gems to scale vaal arc further.

This of course is assuming that Thunderfist is cheap on league start, which is what this build is banking on. Singularity can be easily replaced by a 5c scepter but you lose out on the nice slow.

Assuming that Thunderfist is really expensive, you can easily transition this to a WoC Ignite build with a few passive tree changes.

If you see room for improvements, please do let me know.

PoB: https://pastebin.com/vQ65tMBi