This is the build I use on Steel Path for [Xaku]. You focus on keeping your 4 & 2 up for most sustain, then can cycle between the abilities on their 3 to deal with largest group of enemies.

I keep multiple copies of the corrupted mods at different ranks. Since you only need 200% strength, we [Sacrifice] 9% more strength to make our efficiency more manageable. Completely optional.

With the addition of Archon Shards, either 1 tau-forged crimson or 2 normal crimson shards for strength allows you to replace [Power Drift] with Cuning Drift, maxing out possible range

Between your evasion with your 4, stagger with your 2, & an external healing source the need for [Adaptation] isn't a concern.

I also have a more "casual" build too that only needs 4 forma

Xata's Whisper: A crazy damage bonus with an additional status for Condition-based mods. For more utility this is also probably the only ability worth replacing.
Well of Life vs Blood Altar for subsuming: I use either of these since its a good heal on Xaku/ teammates/ defenses that you don't otherwise have.

• Well of Life works on defenses & [Gaze] can be casted on Well enemies but Well cannot be casted on Gazed enemies. With recent buffs to this as well, it now prevents statuses while in its field

Grasp of [Lohk]: This damage scales with enemy levels, applies void damage, & deals extra damage to enemies hit by your 4. It also can stagger enemies & kill teammates during radiation sorties.

The Lost:
[Gaze]: At 200% power strength, this strips ALL armor & shields to enemies in the range.
Accuse: This converts up to 17 enemies into Thralls (also working on mini-bosses like Zanuka, Gustrag 3, & Necramechs)
Deny: This will suspend any non-thralls in the air & leave them there while your 4 is active.

The Vast Untime: Keeps all of your stock abilities paused while active. You can press again to recast or hold to uncast. Enemies hit are slowed & by a fair amount with our ability strength. They also take more damage by our 2. This is also good for breaking containers if we max out range or for breaking all Hives on Hive missions.

Archon Shard Augmentation

Archon shards allow us to change the build up a bit, give us more range, some more survivability, & increase the efficiency .

• 1x Crimson, Tauforged: +15% ability strength
• 3x Crimson: +10% ability strength
• 1x Azure: +50 energy