Hel, the new generation

[BrazenGordon]

Hel is a warframe of those passed. Of warframes sacrificed for power. She embodies the will of the tenno, who have already sacrificed enough. She is given by the Helminth after so many warframes are subsumed. She has no abilities. All of her power is fully customizable (at no cost of Helminth resources) for all four abilities. Hel's passive is increased Archon shard effectiveness per subsumed warframe for Hel alone. Hel's physical appearence can change based on what abilities are equipped, with a single modifier per ability, including the Helminth exclusive abilities. In terms of lore, she is such a recent addition to the Warframe Line, the tenno actively are involved in making her, marking the next generation of warframes.

[Pakaku]

So a custom set of abilities that basically makes it pointless to play any other Warframe now, and a passive that is useless to anyone who hasn't reached late-game

[Jiminez_Burial]

What you're wanting is just broken.  There would have to be far more restrictions on how the Warframe's abilities can be selected for it to even begin being balanced. 

An ability could only be chosen in the 'slot' that it takes from the existing frame, so you couldn't put Roar and Eclipse on them at the same time because they're both Rhino's and Mirage's 3rd skill.  Or that you have to use at least one of the Helminth exclusive skills such as Golden Instinct.  Or that they have their own set of skills based around supplementing the skills you choose from other Warframes, etc etc. 

If you want to have a Warframe based around the Helminth system then maybe still create a unique Warframe with their own set of skills, but have their passive be that they bypass the 'diminished' aspect of skills.  Maybe link the ability to select a second helminth skill to the 3 Warframe boosts available each week.  I don't know, it'd all be messy.

Edited February 18 by Jiminez_Burial