User blog comment:ClariS/Phrases that Annoy Me/@comment-3475363-20120408082715/@comment-75.75.170.166-20120409015440

Blue Buff has two parts: 20% CDR and 0.5% of max mana/energy per second.

Thus, it belongs to two types of champions: Champions with huge mana problems  (Swain and Anivia are good examples, as they can use their ultimates a lot more with blue buff), and AP carries who don't reach CDR cap  (this can be due to either an unfinished build, an unplanned build, or CDR not being enoungh of a DPS/utility boost.  For Example, a Karthus may not have 40% CDR, so having blue buff will take a lot of time off his ulti's CD)

After that, it's basically anything goes on blue availability. Tryndamere even can get good usage out of Blue due to the CDR on his ulti, though the regen is wasted. If you want it, take it. If you don't want the buff, don't kill the golem.