'Cause I don't have a name for it, I'm just gonna call em Warframe as a [PH] 😛
Passive - Pieces of Warframe's legs or Void tendrils from Warframe are left behind after a bullet jump, returning after a short duration, The returning piece acts as an unstoppable projectile, knocking down enemies in its way to its owner. Movement is not changed while the bits are missing, however an animation (similar to a limp but functionally identical to standard movement) would be neat.
1 - What Once Was - Cycle through 3 (de)Buffs, drawing power from those that came together to build Warframe. Tap 1 to cycle, hold 1 to use the selected buff (like Ivara). Icon designs are based on the aesthetic of the 3 types of bits which compose Warframe. Duration is dependent on, well, duration stat. 25 energy used on cast. Each buff has a special casting noise, similar to those the progenitors may have made.
(Red icon, armor) - +100% Armor, -50% Movement Speed (similar to a Hobbled dragon key)
(Tannish icon, health) - +100% Health, -50% Armor
(Blue icon, shields) - +100% Shields, -50% Health
2 - Separated from Self - The Tendrils within Warframe loosen and relax - dropping all pieces of the body to the ground. The Mass of Tendrils holding Warframe together is unleashed, acting as its own entity, while still being controlled by the player.
Ablilties and weapons are unusable in the Mass. In their places, the Mass can use its tendrils similar to a spear (like Gara's 1, but longer range), allowing pinpoint accurate hits on a single target (eg, taking out a single corpus camera with one shot). Additionally, the Mass can flail around at the press of the [Melee] key, hitting targets within (Range stat * 2 for example) meters. The Mass has a slime-esque movement, and is much less detectable than Warframe itself (but not invisible). While in the Mass, movement speed is increased, but armor and health are sharply decreased. Shields are removed in the Mass. Dying in the Mass begins Reconstruction, with a penalty to Warframe, similar to the Transference Static.
Hitting 2 again begins Reconstruction - a laborous task. The Mass takes time to regather and rebuild Warframe, like a few seconds or something. While Reconstructing, movement, abilities, and weapons are unusable, however Warframe is immune to damage while in Reconstruction. Pretty decent energy drain while in the Mass, but not in Reconstruction.
3 - Break their Minds - Casting on an enemy sends a small Tendril out, where a short animation plays, and the Tendril burrows into the enemy. This enemy then behaves similar to a Revenant Thrall or a Mind Controlled enemy, shooting its previous allies for (Duration). However, at the end of the duration, the enemy will realize what its done, and focus-target Warframe specifically for a short time, similar to if Warframe gained literally the highest threat level possible. 75 energy used on a cast.
4 - Limits Broken - The Tendrils encompassing Warframe are relaxed, yet not severed. The Warframe flails, throws, strikes, and jabs with its pieces. Similar to an Exaulted melee, but with a chaotic, nearly nonsensical combo set. Arms are thrown like a glaive, legs are used as hammers, fingers as spears, tendrils as whips, etc. etc. Basically an amalgamation of multiple Melee types, all at once. Drain while using.