i was lookiing through the jp wiki list of future ssrs and i noticed a buff called sneak attack. ssr cybele for example has it. what does this buff do?

also, im running light and lately im finding sol to be rather "not-as-useful" as she use to be as i can reach the atk down cap without her. are there any strong light teams set ups that dont use her in formation? at least for stuff that doesnt need heavy heals or dispels.