A simple topic if Prometheans where to return how would you implement them?
Personally I would look at what sentinels we have and design them as a ground force. In that I Would keep the prime three Promethean types, Knight, crawler, and watcher. But I would give each a change.
Knight: these digitized warriors are the forerunners main way to distract the flood. they are big tanky, and have melee and close range options. I would remove all but the scattershot from their weapons, maybe give them sentinel beams from time to time. These are there to distract the flood and deal with combat forms in close and dirty so the sentinels above can burn away the infections.
Crawlers: Pure sniper, armed with binary rifles, and high power sentinel beams these are designed to deal with the pure forms and stronger types that might be a threat to the knight while the knight takes the damage. Every knight has a pack of them around 3-5 depending on their rank.
Watchers: These are drones, once they where Ungoy but now they are a deployable support and flush drone, still able to revive knights and crawlers. Their main focus is using light bursts from a constructor beam to deal with pod forms, other then that they are armed with the ability to pick up and fire any one handed weapon and launch grenades. Though they must return to their knight to resupply grenades.
These would be tacticly distinct form the covenant as each knight would have 3-5 crawlers and a watcher working as a unit. Taking out the knight would force the crawlers and watchers into a more feral mode as they don’t have their commander. Unlike taking out an elite with grunts, they will not panic instead they will focus the one who killed the knight. The Crawlers even activating self destruct systems if teh watcher is killed and can not bring back the knight.
The idea with this rework is the Knight would be the key to its group. acting as a local sentinel command unit, commanding small ground squads while the flying drones do their own work.