Build meant for Endurance missions where any other companion would die.

Sly and Panzer Vulpaphylas are almost identical in usage. Panzer offers bonus damage by proccing Viral on enemies, while Sly occasionally saves you from damage, which could be quite valuable for Arbitrations. They use the same set of mods aside from their unique mods (Sly/Panzer Devolution & Survival Instinct/[Viral Quills]).

Because the Devolution mod makes the Kavat essentially immortal there's no big need for survivability mods. So the only 2 survivability mods being used in the build are [Tek Enhance] and Hastened Deflection because they are the only sources of scaling survivability.
Hastened Deflection(+Shield Recharge) means better shield-gating invulnerability.
Shield-gating grants invulnerability when shield is broken. The duration of invulnerability scales from 0.3 to 1 sec depending on how much shield they have when it is broken.

The two Synth mods offer passive reload of holstered weapons. They're also amazing support for [Health Conversion] builds:
[Synth Deconstruct] is a source of Health Orbs, which do not drop naturally (excluding crates and a few Grineer units) and [Synth Fiber] allows your frame to pick up Health Orbs at full health. Meaning you don’t need to take damage to stack up [Health Conversion].