[Piercing Navigator] allows [Ivara] to use extremely weak weapons against Eidolons. Navigator needs a very specific build to work correctly and we choose a subsumed ability that either increases our damage or protects us from status effects.

Empower is chosen because it synergizes with the extremely low duration that you need for Navigator. The ability strength has fairly diminished returns so you can also choose any of the damage buffs like Roar or Nourish but they require extremely tight timing due to your minimum duration.

Fire Walker and Spellbind can [Protect] you from status effects if you don't have a [Harrow] on the team. Fire Walker barely lasts long enough to get you through a full Eidolon scream but Spellbind needs a bit more duration so you have to drop [Fleeting Expertise] by a couple ranks.

[Artemis Bow] is replaced because it has no purpose in this build. You can replace Quiver if you're planning on using this in an [Artemis Bow] Eidolon setup.

[Power Drift] can be replaced by [Coaction Drift] and [Augur Secrets] can be replaced by [Streamline] depending on your team composition.

Arcane Avenger and Arcane [Guardian] synergize with Navigator as your frame stands completely still tanking hits while you're flying the projectile into the Eidolon. [Guardian] can be replaced with Arcane Nullifier if you don't have a [Harrow].