Honestly dunno what type of passive ability this frame would have, maybe a void burst where you gain X amount of energy a second.
1st Ability - Tendrils (kinda like Nidus where he stomps the ground, void-like tendrils will come up out of the ground sapping energy + health from the enemy)
2nd Abilty - Void Surge (causes enemies to freeze for a few moments, sapping energy + health for you & your team whilst jamming enemy weapons)
3rd Ability - Ethereal (become invulnerable for a period of time, incoming dmg is stacked & reflected back on the enemy)
4th Ability - Tendril Slam (Warframe can turn one arm into a large mass of void tendrils, hitting enemies or slamming the ground will grant a significant amount of energy depending on 3rd's stack ability)
And that's it. I guess.