So, two things I was thinking about:
How would you guys feel about a gameplay mechanic being added to "paint" enemies in death? Let me clarify: it could work in Arena or Warzone, though for deathcam reasons Arena would make more sense. Once you're killed, your body ragdolls and "settles" as normal. For painting to work, there are two prerequisites: you have to keep your camera on your corpse, meaning you're sacrificing viewing what's happening to your teammates, and your copse also has to be present, meaning getting flung off the map / disintegrated / etc. prevents it from happening.
During that brief 5 to 6-second window as you're awaiting a respawn, you can hold down your Scope button (so generally either right-click or LT) and you'll begin a charge that takes roughly as long as a Spartan Laser, being 3-4 seconds - giving you enough time to comfortably evaluate your corpse's orientation in post and whether or not painting is worth it. If any enemies are in range of your corpse (let's say the painting range relative to your corpse is about the same size as a rocket's splash radius) for the entire duration of your charge-up, they'll be outlined or "spotted" for all of your teammates, but not you. So, in other words, it's basically Martyrdom Promethean Vision, though with a number of checks and balances in place. Enemies that are painted are alerted that they've been spotted (possibly with a UI element around your corpse), and they'll remain spotted indefinitely unless they vacate out of range of the corpse (or until you die again).
While it may not necessarily clarify any information that team chat wouldn't, I think it'd be an interesting way to help prevent camping and aid in conveying info to teammates that aren't communicating, with the possibility of Spartan banter being added for it. e.g.
"Lost a teammate!"
*vwoooooooooop*
*DWEEE*
"Downed teammate painted a target!"
"Lost one to a Binary Rifle!"
*vwoooooooooop*
*DWEEE*
"Enemies spotted on their X!"
etc.
It'd also probably be more effective in objective gametypes than deathmatch-based ones, especially something like Strongholds where enemies have a habit of staying out of sight but still in the capture point.
Which brings me to my second point: how would you guys feel about player-wielded "kinetic bolt" / Promethean weapons disintegrating the equipment their victims had, in addition to vaporizing the bodies? I don't think I'd want stray Promethean AI wiping it out because it'd suck to lose Warzone weapons to mobs, but I think in Arena especially it'd give Promethean weapons a little extra oomph and illustrate them as being especially dangerous in situations where you also carried a power weapon - not to mention if you consider possibilities like derezzing an enemy carrying your flag causing it to return instantly or something. It'd also have a modicum more importance in a metagame where "painting" existed, because it'd mean the enemy would be shutting you out of being able to spot them.
