As a [Hildryn] main, i only use this. so many stacking DOT's will actually fairly quickly kill everything around you, especially grineer. Obv infested is an issue, but with enough enemies and [Blazing Pillage] you can get by, with some effort, but its just not suited for that. Deimos enemies have some armor which will get you by.

I personally have archon shards in health and health [Regen], without them id reccomend [Primed Vigor] on top of [Adaptation].

The aura is also speculative, i used [Holster Amp] pre forma for a very long time.

Elemental ward needs to be electric, as it will deal damage based on how much shields you spend, which is why this is a neg efficiency build, and does so much damage. i don't know why people put [Adaptation] on [Hildryn] besides laziness and not wanting to just outlaw armor mapwide, but it will actively harm this build, as its mainly thorns.
Optionally you could put it on top of balefire. I've found I haven't used it in a while and been wanting to use aegis.