(Sorry if this isn't the right board to post this on; it's not exactly Feedback and I didn't see a general "Suggestions" forum.)
I'm enjoying the Kuva Lich (a.k.a. Kingpin) system so far. Even though I'm far from "done" with it, I find myself already thinking of the future. I recall Rebecca mentioning that the system will (someday) extend to other factions as well,so I was thinking... what would they be called? What would their origins be (assuming Kuva remains a Grineer thing and isn't just used for all of them)? Personally, I hope they choose to have the terminology themed around fantasy monsters, giving each faction a unique flair. I've laid out some ideas below. DE: feel free to use any or all of it if you think they're good. 😉 Other players: what are your thoughts?
Power Source: Sentient Amalgamation run rampant.
Rationale: Chimera in mythology are creatures composed of parts from several other creatures. Amalgams are fusions of Corpus and Sentinet parts.
Ascension: When an unstable prototype/reject amalgam is struck down by a Tenno, the sentient cells go into overdrive and try to "adapt" to the threat, causing transformation into a Nemesis-type unit tailored to the Warframe and/or powers used to "kill" it. Corpus special agents (or Alad V himself) extract the unit the same way the Kuva Guardian does for the larvae.
Power Source: Mutation
Rationale: "Colossus" fits thematically with "Juggernaut" and "Golem." (Would have suggested Golem instead if it wasn't already in use.) Could also serve as a call back to the Colossus in Dark Sector, as it acted sort of like a Nemesis by appearing and leaving until eventually dying after a final Boss Battle with Hayden.
Ascension: The equivalent to a kuva larva could be a special type of Infested Spawn Pod that sits gestating. A Tenno would logically try to kill the pod to prevent whatever is inside from being fully formed, but when they use the Parazon to perform Mercy, the biomass fights back for a moment before releasing the Warframe and starts mutating based on material transferred during the physical contact. An infested 'hive mind' calls the creature away and it escapes the mission to finish its transformation into a Nemesis-type unit.
Power Source: Sentient Evolution/Transformation
Rationale: Homonculi are artificial human-like beings created through Alchemy. Sentients were artificially created by the Orokin.
Ascension: Some Sentients begin focusing their innate ability to change their form and evolve towards becoming more like the Warframes. It could be with the intention of infiltration, or a hope that it will somehow lead to them becoming resistant to the Void energies. In any case, the 'larvae' form would be like a Mimic trying to take on a humanoid shape. If a Warframe comes along and uses Mercy, it attempts to escape death by mimicing that Warframe. (Perhaps some genetic data passes into them through the Parazon?) Instead of becoming a copy, though, it takes on a unique Nemesis-type unit with related powers. (Idea: instead of a helmet on a shoulder pad, these could literally have a head shaped like the progenitor warframe's helmet.)