After reading a lot in the forums i found some topics in there is some kind features to playing with other for the some goal - guild, factions, fortresses, dungeons. There where some suggestions how will them work, but the cooperative gameplay mechanism is interesting me overall so think this topic needed.
Until now i can play pvp against my girlfriend, my workmates, because their avatars on my map and can start close pvp combat. But we are on different lvl, so is this not so much fun. What we need is play together against monsters/others/fortresses/dungeons.
Well, two or more players against a monster is a bit overpowered on the same lvl, but can be fun. Ingame mechanism? For example spells casting on myself could be affect all my group! So when we decide to play coop we invite the nearby player and there will be option to pvp or coop - we choose coop. Then if any of us or the group leader attack a monster/fortress then we all we see enemy. We cast spell invidually, our attacking spells take effect on the enemy, but our defensive spells (and heal) will affect every members of our groups.
I just made a thread about this..
The idea of Melin is great, please read his link above too, and upvote if you like it!