User blog comment:JmLyan/Arath, the Power Charger/@comment-13536822-20130802024421/@comment-7481207-20130802112619

If you look at his ultimate, you'll see that both Maxdrive and Overdrive give you max charges, allowing you to use one tier 3 spell followed by either an extra damaging tier 3 spell or a mark empowered tier 3 spell.

Also charge beam can fully restore charges if it hits at least three champions and at least one Hyper marked enemy, allowing him to follow up with a tier 3 spell.