Never played warframe, so I wouldn't know. What's the stalker supposed to be like?

Without going too deeply into the lore... Warframes were made by a 'superior' race that was losing a war against another 'superior' race, that was taking their own technology and turning it against them. Warframes were their last ditch effort, and it worked. Warframes were then used to essentially reign everything back in. Sometime after finally regaining the peace, the Warframes essentially assassinated the entire race that created them, with a few of their lower guardians remaining or surviving, one of these becomes the Stalker, driven by madness to avenge the loss. The Stalker, after the coupe throws himself into the same place were the Warframe's powers originated from, whether it was an attempt at suicide or a desperate bid to gain power is up for debate. The Warframes go into cryosleep at some point before/ as this happens, so they don't have a clue about it. Hundreds of years go by, and the Stalker is still alive and kicking, essentially haunting players after they kill bosses at random, given a deathmark and an anonymous message in their inbox stating "Your actions have consequences.." The Stalker has several Warframe abilities, as well as its own unique 'Dispel'. It is immune to all Warframe abilities and can strip you of your buffs/powers. If you look at a side to side of the "poster frame", Excalibur; and the Stalker, they have the same Warframe, save for the fact that the Stalker has its own unique helmet. If you manage to defeat the Stalker, you have a chance to get one of his three weapons, each with their own special benefits to damage or critical chance. If Destiny were to incorporate something like this, perhaps it could drop legendary engrams/exotic engrams, but with a very slim chance of spawning. I would welcome it.