Real talk here.

200% duration is more than enough for all your needs
Efficiency takes a hit to make room for everything else, but with energize it should still be servicable if you pick an orb or 2
Range is like, super important for [Octavia] to provide her buff for teammates and for her mallet to be efficient at covering the point. (but this build is for big dmg, and 124% will suffice)
The strenght is to provide big dmg buff on your amp, and for your mallet to kick some serious ass.

The Ball is hot garbage, and should almost never be used.

Strategy is:

Arrive at point.
Throw down 1.
Start your 3.
Clap down a 4.

The order is best for animation purpose, as they chain.
Now you just go stealth and watch things die.
Your 1 and 3 will run out at the same time, while 4 will continue on a bit longer.
Use this to always keep track of when to refresh mallet, even while roaming outside it's area.
You may shoot abit too, while inside the amp, as this thing will do a pretty good dmg boost with this build.
There for have your second Arcane be something that buffs your weapon of choice, for me it's my Vectis Prime.

You could change out Constitution with on of the Augurs (reach/secrets) or [Primed Flow], depending on situation, as this build will still work plenty fine without those 28% duration.
Secrets for when you want even more dmg
[Reach] for when you require more range to cover the point (Range is always good)
[Flow] for those pesky times you suffer energy reduction, and for easier energy mangement if you prefer to not empty out every time you recast.

Now you can play your tune, kick back and baby sit the defence point with your mallet, while you're staying stealth and praying that no breeze comes your way. This build has zero survivabilty in end game content, when out of stealth, so don't be out of stealth. mallet < amp < stealth.

Go make Clem proud you darn tenno skoom.