Freaking cast it in
this. Huge MAcc Boost.
Look at it like this:
* Most (all) high level NMs these days aren't sleepable.
* Most normal mobs are either immune to repose or don't particularly resist it.
* It gets a huge MAcc boost.
If you're reposing anything with quasi-skilled Divine magic, it will not matter one iota whether you have any MAcc in gear. Use Haste, as Draylo suggested. You might as well focus on Conserve MP after you've capped Haste, because added MAcc simply won't matter.