A build geared toward multi-hour Endurance runs, where you can't rely on other companions to stay alive.

Panzer/Sly Vulpaphyla are preferable to Djinn because they have better up-time(less time dead when reviving).

Recommended weapon and build: https://overframe.gg/build/141553

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].
[Fatal Attraction] offers some nice CC; it forces enemies within 20 meters to stop attacking and walk slowly toward [Djinn] for 5 seconds, after which it staggers enemies within 6 meters (30s cooldown). Note: Order is important for Fatal Attraction; it needs to be positioned before other precept mods.
Hastened Deflection(+Shield Recharge) for better shield-gating invulnerability. Shield-gating grants invulnerability when shield is broken. The duration of invulnerability is 1 second if the shield is full and 0.3sec if it isn't.
Guardian and Shield Charger boost your frame's shield-gating capabilities.