Board Thread:Versus Battles/@comment-33601685-20181108021429/@comment-28876888-20181115113543

For mindhax, I've realized Boian likely scales above the Elder Brain, which is CR 14 as of 5e. CR 13 is the minimum for Low 7-B rating, and AFAIK Boian beat down tons of the Low 7-Bs easily, hence his 7-B rating.

That said. An Elder Brain is a sentient hivemind of Mind Flayers, absorbing all past descendents of a Mind Flayer colony into its own hivemind. A colony can range from a small outpost to an actual city (cities in D&D can be upwards of 100,000 beings, if Greyhawk is any evidence) and the Elder Brain is... all of those minds. Each of those minds in of itself was capable of maintaining slaves via domination.

Not sure how high that would be, but scaling to the Elder Brain causes some pretty crazy mindfuckery and if Boian's mindhax comes from being a vampire (as I suspect it does), it is not in fact magic.