A stillborn project for monetizing MediaWiki.
Systemd is reported to be optional, but I don't have information on that.
My past experiences were dismal enough that I don't want to bother trying Gentoo again.
An AddOn to make raid fights easier. Although Blizzard added similar functionality into many of their fights, I consider this absolutely mandatory.
For most people I'd say "just install it". It does need some significant configuration for many fights, and for my minimalistic taste. I mean, who the fuck cares about an enrage timer bar?
Note that, to reduce the size/complexity of the addon, they maintain the current expansion's content as one addon, and other expansions in other addons (listed on their page).