I was thinking about the changes regarding the importance of mana conservation in cataclysm and had an idea of recreating the mana battery.
I thought that a fun use for disc would be to greatly nerf their healing, but in return buff bubbles (and maybe other absorbs) and also grant them mana battery abilities.
For example instead of casting a heal, you would cast a mana heal!
Disc is already master of the mana burn so this just seems like it would fit in and it would be a unique way to support a large raids without simply being the top healer or dps (kinda like posting who had the most cleanses on heigan).
There was one spec that served as a mana battery in BC, the shadow priest, and as a result they felt like a requirement for raids. To balance this you could add similar utility to another class, like demo locks or arcane mages.
It would certainly be a completely different playstyle, but would anyone else enjoy this as an option?