Idea- Spartan killers campaign multiplayer adversaries

[RogueForce21]

Since the introduction of the spartan killers I had wondered if that there could be a way to do a darksouls type invasion multiplayer in the campaign where some spartan killers (players) would drop down to hunt the main players. Function could be set on or off of course, but would make it fun for sure. Maybe spawn as any enemy even grunt squad? Maybe the more you win the stronger enemy you can become like grunt all the way to brute? until you fail? Could add lots of replayability and would make fun multiplayer if you could use different types of troops, but hey just an idea. If this is 10 year game it would surely add longer life.