User blog comment:Willbachbakal/(Item Concept) Fixing Mana/@comment-1920550-20160319060124

So Meddler noted in a boards post that they are planning on shifting MP5 items such as Morello into flat mana items, making mana stacking a more core aspect to the mage class (much like crit is for ADCs now), while making MP5 more of a support stat.

http://boards.na.leagueoflegends.com/en/c/gameplay-balance/vZKZprwH-meddler-could-you-tell-us-something-about-the-itemization-changes-for-mages-please?comment=000000070000000100000000