Hydroid Build - Poseidon Energy!
Imagine playing a frame and use its full potential, just like [Gauss] and [Wisp] but with extra loot and fun.
This build is based on max duration and infinite energy, decent range (since big range works bad with [Hydroid], because he has only 20 tentacles max when charged his 4).
His 4 last 50.8 seconds, his 1 last 25 seconds, fully charged.
You need Dethcube as companion for energy orbs and health orbs, you should use this build
Arcane Energize is important if you really don't want to worry about energy at all, because [Pilfering Swarm] gives you hp and energy orbs always + [Dethcube] generates orbs + arcane energize proc = your energy pool is always full, rank 5 isnt necessary, rank 3 works fine as well.
Arcane [Guardian] for survivability, you can swap it with Aegis if you like.
Magus Elevate for burst heal in tough situations, Focus school on your choice.
This build was tested on Kuva Survival, Arbitrations, 1hour+ survival in Mot (Void Survival with Uncle Vor), 1hour+ on Dark Sector missions.
If things get tough just use [Hydroid]'s 2 or 3. Tidal Surge gives invulnerability while you surf, Undertow gives invulnerability as long as you have energy, so you can just drown high armor enemies, since Undertow has scaling damage.
You can swap [Cunning Drift] with [Sure Footed] if you're tired of knockdowns, 2nd forma is need only for this swap, if you're not after farm you can swap [Pilfering Swarm] with Corrosive Barrage, since enemy's armor is nerfed its extremely easy, and since you cant overstrip armor, corrosive procs will deal decent damage.
As for weapons i suggest [Kuva Bramma] and [Kuva Nukor], coz it's easy to kill groups of enemies which were staggered with 1st and 4th abilities, also you can use [Rakta Dark Dagger] coz it restores shields and give overshields, if you decide to go melee.
Hope you guys tried and liked this build, sorry for the novel, but i have to explain how exactly to play [Hydroid] and dont die, cheers! :)