Guild Wars 2

Once you 100% a map a new NPC appears at the entrances to said map. They will then have a list of gambits to increase the difficulty while also increasing the rewards. The gambits can only be added or removed at these places and they would be shared with your party after a vote, once added your party would lock.

They could also be used in dungeons.

Edit——
I guess I should of added that these would be new gambits. Like an under leveled one, a tethered to your group, or locking out healing utilities and elites.

That would never work out.

A lot of the Gambits only make sense because you’re alone and in a restricted space. For example, Hamstring would make very little difference in general PvE. On Fire can be fully counteracted with your healing skill. Squeamish isn’t an issue in PvE as most classes already deal a hefty amount of damage.

That only leaves you with Frailty and Crowd Favorite. Well, most attacks from big mobs are already one-shotting you, so Frailty wouldn’t do much. Crowd Favorite, on the other hand, cannot even be properly implemented outside of instances, not to mention that even then it could be abused.