5 Forma [Xaku] build with Roar in place of [Xata]'s Whisper.

179% Duration: 40+ seconds on The Vast Untime and 50+ seconds on Roar.
250% Range: 15 max targets on GoL and 20m radius on [Gaze].
194% Strength: 97% armor reduction on [Gaze] and 97 base scaling damage on GoL, 58% extra Roar damage.

I'd recommed replacing [Augur Message] with either another Augur mod, [Energy Conversion], [Streamline], or [Adaptation]. If you choose [Augur Secrets] or [Energy Conversion], replace [Corrosive Projection] with [Energy Siphon] as the Aura, or if you can spare the Aura forma put on [Growing Power] and forget about the previous 2 mods.

Feel free to replace Arcane Arachne with anything else, as it's only here to boost the damage of GoL even further.

The main play style in this build is to lock down an area with two casts of [Gaze], cast GoL in a crowd, and buff with Roar and The Vast Untime to have it be your main damage source. Best in Defense and Survival.