My idea in short is to add status effects to players in a certain area on certain maps or around certain monsters or bosses.
For example, for every or some stages in battle arena you could add effects until the players move on to the next stage, start with a slight +attack or health regen and move gradually into -defence and a slow poison. If im correct theres a certain mission on guildwars where something similar occures, you have to race against the status effects and finish the stage before they kill you. Also if a poison makes it too hard because players want to wait for skills to recharge you can make the effect be removed when certain conditions are met.
The same idea could be used for boss' (or normal monsters) skills or attributes. When the fight starts the boss or area could have an aura effecting player defence or something and the amount its decreased could increase as the fight goes on, the effect could randomly change, an event could trigger a change such as an item used, a player skill used or a boss could have there own skill that changes it.
Im not saying to add this to everything that would be far too much, but it would add another element of fun to a selected few missions and monsters. Maybe the effects could be related to performance. That's my idea at the moment, i have plenty more to post, i hope you like it.
