Method Raid Tools is a required addon most used for its global notes to help all raiders know key ability use timings. 

This directly feeds into a lot of weakauras and addons that help raid timings and to avoid ability overlap. EG: we need a roar, oops 2 druids both used Stampeding Roar.

If you have any issues with MRT note not showing ensure you use '/mrt note' as this command toggles it on and off