I would love to see two things in destiny. 1. A boss run mode. Have it set to a higher difficulty, with limited/no respawns and see how many bosses you can take down in a row. 2. Enemy hoard mode. Fight off endless waves of enemies and every few minutes add new enemies or modifiers, like light switch ect. Start out fighting weak enemies and end up, if you are good enough, fighting majors/elites with 8-10 modifiers on. Both of these modes/playlists would be a great way for people to "earn" rewards with the better items more likely to drop the better you do.
Calmity Haze, I like the horde mode idea..... if 3 to 6 characters were given a "HOLD THE LINE !" Mission where they had to hold out for 15 to 20 minutes against a Horde of enemies....until the reinforcements showed up...or until evac.....similar to the action in Mass Effect 3, that would be an interesting experience. What about a multi-stage mission ? Team is dropped into hot zone: hold position / wipe out enemies / down load info / counter-attack / bug-out / get to fortress / hold out vs Horde or attack Horde on the move with vehicles and with everything at your disposal BEFORE the Enemy destroys an Allied target: War Satellite / Defensive Orbital Gun / Courier / Artifact / Recovered Relic of the Darkness / of the Light / Traveller's Replacement Batteries.