My goal was to create an endgame [Hydroid Prime] and prove to my friends that [Hydroid] is in fact not the worst warframe in the game. I admit there are better frames out there to use that can do what [Hydroid] does a lot better however i still feel like his kit is a it better then people are saying it is. Lemme explain the build:

Pillage, [Hydroid] naturally has a lot of shield so why not give him more? personally i always saw the use of tempest barrage as a way of armor stripping, I know it can be used as a way of crowd control too but i think his fourth ability has that handled. Pillage allows you to strip a lot more enemies as well as provide another means of survivability. The addition of overshields also gives us the opportunity to have increased ability duration more constantly thanks to Molt Efficiency. It's also worth noting that you can use pillage while in undertow.

Energy Siphon is nice to have, got it here in the off chance i run out of energy but you could honestly replace it with Corrosive Projection or even Empowered Blades if you wanna take advantage of your high shields and make things interesting.

Power Drift is here for that minor increase in ability strength as well as giving us a little knock down resistance on the side

Transient Fortitude & Umbral Intensify are here for that major boost in ability strength, making our tentacles hit harder and making Pillage strip up to 53% of armor with each cast

Primed flow gives us that juicy energy pool, Primed continuity is here to offset that negative duration from transient fortitude, & Augur reach is here to provide us with some needed range as well as refund our shields when using our abilities

Tidal Impunity is here to provide added survivability, pillage works very well against grineer and corpus however is really ineffective against infested. the real danger infested presents is toxin, so [Tidal Impunity] helps greatly with that. It also makes the energy consumption waaaay better going from 50 energy to 15 energy cost for tidal surge on each cast

Equilibrium is here to provide us energy for accumulating health orbs, something we will be doing to take advantage of Arcane blessing & Health Conversion is here to give us a large boost in armor for picking up health orbs which i will say again WE WILL BE DOING

Arcane blessing is the crux of this build. As i'm sure you have noticed [Hydroid] has a rather below average health pool, Arcane Blessing solves this problem. Everytime you pick up a health orb your health pool increases by 24 health per orb, this means at a max 50 stacks you will have 1200 additional health. because we have Equilibrium you will also get energy whenever you pick up health orbs. And because we have Health conversion we will also get a boost to armor for picking up health orbs.

now the question that comes up is how do i generate health orbs constantly?
easy. the synth set.
Synth Deconstruct makes it so that anyone your companion injures has a 25% chance of dropping a health orb.
Synth Fiber gives companions 100% armor increase for 12 seconds upon picking up a health orb. this may seem less exciting however this mod allows us to infinitely pick up health orbs

the synergy here to perfect. I use a Panzer Vulpaphyla for it's mini [Saryn] ability, injuring the most enemies allowing me to get health orbs really often.

I also use this broken scepter build (https://overframe.gg/build/474185/broken-scepter/health-orb-gen/) as a way getting health orbs as a backup.

and finally Molt Efficiency is here to provide us with even more ability duration when we have our shields up which is almost all the time.

I'm very proud of this build, i think it's really strong against all the factions and works best in survival and defense type missions. Your tentacles probably won't kill a lot of high level enemies but they'll hold em down for your weapons to do their job. When ever your in a pickle you can always pop your undertow for invincibility. you can spam tidal surge to move around while like that or pop tidal surge for it's incredible 12 seconds of status immunity for you AND your allies. Overall [Hydroid] has become a lot more enjoyable to me thanks to this build and i hope the feeling is mutual.