Specifically Diva Intervention charges her BB3 purely off of the sekhmet from the BB3, allowing an infinite chain, providing you don't mess up the specific combo. Diva's SA allows her to reduce enemy BB and charge her own by % per hit, meaning a full charge attack, dash, down, dash will fully charge your BB3 again. The optimal thing is to have your opponent against the very edge, otherwise, you'll have to dash as soon as you hit the ground and charge and release the charge attack perfectly, otherwise you won't charge the BB3 fully.
Outside of that, my common use of sekhmet is <Ground combo -> Laucher -> Sekhmet's Bite -> Dash -> Down -> Dash -> Charge attack -> Down>