How about a PvE Crucible? Create a Gladiatorial Arena that a guardian could solo or up to 3 man Fireteam can tackle. You can choose your level of difficulty, like the strikes. If you or your entire team dies, game over, no prizes. If you win, you get your ammo filled and you go to the next, progressively harder level, until you wipe (think Tetris). There will be ammo drops during the battles, but no synth. Prizes drop after every battle is won, but also get progressively better as the battles get harder. Prizes and levels should be varied based on if you go in solo or Fireteam. There should also be a full set Gladiator Armor and Weapons to be won. Plus the addition of Gladiator Vendors called "The Sanctum". I know it is a bit WoW ish, but it would be fun.