So first build on here because I have become obsessed with Wisp as one of the best supports in my opinion. It took me a lot of time to figure out how I would build wisp and finally settled on this and other players love it in game. It is quite expensive using 7 forma (including an umbral forma) to make it work. Unfortunately at least 1 umbral forma is necessary for this build and then forma on every other spot (also changing the native polarities), but if you happen to have two umbral forma or even 3, it could shave a few forma rounds off.
I wanted this build to be great for helping your team. This build is mainly intended for stationary or small map situations like defense, mobile defense, index, etc.
While strength is the most important factor in this build, I did decide to sacrifice 30% for the power donation to give my teammates the extra strength boost (with the final builds strength resulting in 370%, i do not think its too much of an issue for the motes as even at 340%, they will be amazing).
Duration and range are both important to have at least a little extra for which comes from the primed continuity and stretch. I have seen builds with very little range and it honestly becomes annoying to get the buffs as the circles are very tiny, with this build it has good range and duration for the buffs.
You may be looking at the efficiency and think right away with 45% efficiency and no flow mod to increase pool, this is too unreasonable, but compared to other frames, the cost for the motes is pretty cheap plus they stay down unless you try to place more than 6. With arcane energize, you can easily refill your pool, and then once the motes are down they are there until you choose to replace them, so for missions where it is a small map or you are defending a small area, its not a big deal and the strength easily makes up for it.
Wisps motes (or her 1st ability)
Power Donation - Steel Charge (or any other aura if you dont care for either, but then you lack mod capacity for build)
Stretch - Augur Reach (Some range is important, but the augur bonus not very useful here, so extra range from stretch good)
Energize while not required, can be extremely helpful in being able to get your motes down especially with the low efficiency
I read up that you could have two of the same arcanes on a warframe and they can proc independently (im still somewhat newer still, only 3 months and mr15 and only own 1 energize so i am not positive on this), if this is true, I would say go for two energizes, if not then 2nd spot is open
I did just recently unlock the helminth and was debating between Proteas dispensary or Rhinos roar to subsume in to Wisp, ended up going with roar for damage buff to help be a good support in more aspects.
Wisp also becomes a pretty good tank herself with the umbral vitality/fiber combined with the insane healing/health this build gives. I have seen builds with adaptation, but personally I wanted to focus on being the best wisp for my team rather than making myself an even better tank with adaptation.