Originally Posted by magic0113
gragas is the direct counter to cassio
I fail to see why. Gragas counters burst casters because his W significantly reduces the damage of a 1 or 2 skill high damage burst. Cassio's damage relies on low cooldowns and damage over time, which are not significantly reduced by his W. Her skillshots are easier to land than his and have comparable range.
To the OP:
Counter skillshot champions with non-skillshot champions. In addition to the aforementioned Kass and LB, you can face cassi with:
Vlad (if you can survive long enough to get some items, you won't really be killable in lane),
Swain (for the same reason),
Sion (because of the lack of skillshots),
Ahri (not really a skillshot champion, push RWRR and you can burst her down easily)
Any champ with whom you can put damage on her without taking damage in return.