Fairly Standard Eidolon [Harrow] but with Umbral Mods because why not?

[Blind Rage] and [Streamline] can be swapped out for [Transient Fortitude] and [Augur Message] for more efficiency at the cost of a small amount of duration and strength. Slightly less wiggle room for Covenant but easier on your energy pad consumption.

[Blind Rage] could also be dropped for [Hunter Adrenaline].

[Coaction Drift] can be swapped out for [Handspring] should it already be covered by team members.

Arcane Options:

Energize
Commonly paired with a [Sahasa Kubrow] for their [Dig] mod. [Dig] at max rank will always '[Dig] up' two items (energy orbs, health orbs, or ammo) with a decent chance for a third item. Energy and health orbs are prioritized drops once the respective pool drops below roughly 80% according to the wiki. [Dig] has a 15s cd and a 5 second 'cast' time.

[Guardian]
Adds another level of tankiness while Covenant is on CD.

Everything else
[Harrow] doesn't really need anything other than nullifier. Tanky arcanes are good options as [Harrow] shouldn't be attacking synovias in a proper group.

[Wyrm] with the [Negate] mod can be used. [Negate] can be consumed by knockdowns or other status procs and has a 5s cd.

NOTE: Really don't know what the meta is right now with helminth abilities in the mix but the build should still work as intended.