Brief Respite in the aura for shield gating. Whenever your shields break, simply press 4.
Exilus mod can be whatever you want. Could use Cunning/Power Drift for more range/strength, [Nira's Anguish] if you're using a slam melee, Kavats Grace to resist hard landings caused by her 1 and 4, etc. Just choose whatever suits your needs most.
[Blending Talons] is incredibly useful since it turns Seeking [Talons] into an aoe tap ability. This overall just makes the ability easier and faster to use. By default the aoe has a 9 meter radius but with 235% range that becomes 21.15 meters. You can also still use the hold variant which can be useful in different situations. Imo this is a must use mod for Garuda.
Garuda does not require a lot of duration, so Primed Continuity is enough.
Primed Flow for a massive energy pool of 912.
Since Nourish buffs Bloodlettings energy return, we can comfortably run 45% efficiency with no real drawbacks. However, if you choose to use any of the alternative Helminth abilities, I would recommend replacing Blind Rage with Transient Fortitude or you'll find yourself having to cast Bloodletting constantly.
235% range for over 20 meter aoe on both Blending Talons and the Dread Heart nuke.
High power strength for dealing more damage and increasing Nourishes energy and viral damage multipliers.
[Primed Redirection] gives [Garuda] enough shields for a 2.4 second shield gate. Because we have negative efficiency and abilities cost lots of energy, it will be quite easy to refill all your shields in just a few ability casts. However, this mod slot is also flexible.
Molt Reconstruct is similar to [Brief Respite] but it generates health on energy usage instead of shields. This basically gives you infinite energy from Bloodletting since you can instantly heal whenever you want by just casting 1, 2, or 4.
The second arcane is up to you. Depending on what you use [Garuda] for you could run a melee or gun arcane or simply pump more stats into your warframe with something like Molt Augmented. The possibilities are endless with Garuda.