Maybe open up mercury in a supersizrd crucible type map with patrol capabilities. Key difference from just regular crucible of course being an untimed environment, and the quests and missions being geared much like patrol missions. Just, oh dead orbit wants me to scout out this area ok. New monarchy wants me to kill some enemy players, sure let me go hunt some down. No, you wouldn't get immediate rewards like PvP, but bungie is creative and PvP is a specialty of theirs, they could think of something. Cannon being what it is, just say vex are active in that area, but shaxx wants to make sure guardians can handle mutltiple targets at once with the recent talks with the reef and the threat of the taken.