This is the [Wisp] build I use, it's very high investment but its super solid, carried me through steel path no problem, casual playstyle. The idea is simple, the only ability I ever care to use is Reservoirs so that's what I built around. I [Sacrifice] range to increase duration because I don't want to have to sit on top of them all game, I enhance strength so I can out heal nearly all damage and increase my firerate to the maximum. What arcanes you use don't matter much, energy isn't much of a concern and neither is health so you can choose whatever you want, I use [Guardian] for increased survivability and Precision to increase the damage of my [Laetum]. I don't include Molt because I rarely run missions that last long enough for it to matter.
For Archon Shards again you can use whatever you want, personally I used 3 crimson shards to increase power strength to a round 400 and used two azure shards to increase armor.

I don't use [Growing Power] because it's too situational to be useful IMO, requires to first proc a status on an enemy then lay my reservoirs to be useful, same with [Energy Conversion], the odds of you procing both at the same time is extremely slim so I'd much rather settle for something reliable. I also don't use [Fused Reservoir] because I honestly just find it a waste of a slot, saves me maybe 3 seconds.