This may sound strange but hear me out.
I love playing pinball and there may be elements of pinball that could be integrated into WoW.
1. Bumpers - How about a raid where a game mechanic is a ball of energy is bouncing around and must be prevented from reaching a certain area. it moves slowly but if it enters a set of "bumpers" it rattles around and fires out randomly. Some players must be positioned in a spot to catch the ball if it flies near a certain area or else everyone takes damage.
2. Dropdown targets - Maybe in a raid there is a ball of energy bouncing around. One player is assigned an Aegis-type device that deflects the ball away whenever it comes close. The goal is to deflect it towards a bank of targets and hit them all to unlock something or maybe turn off a raid mechanic.
3. Jackpots - How about a difficult world quest that has a dynamic jackpot reward. The jackpot rewards increases over time the longer it goes without being completed. So image some difficult world quest where it starts out with a 600g reward that increases by 150g every 15 minutes. Failed attempts add 200g to the jackpot.