I know. 3 Umbral forma. Spooky. But Adaptation is broken (if you have [Adaptation] stacks still left as you go into the gate, [Adaptation] will not work when you go back into PoE), thus Umbral Fiber nearly doubles your Effective Hit Points.

Solo Eidolon [Volt] build. I use [Zenith] for waters and [Vermisplicer] for other limbs and capshots. This build works fine with rivenless [Perigale] or [Rubico] (will need some sniper combo).