Zac

Olaf

Olaf counters the knock up from Sion his Q and R with his ultimate, also the slow of Sion his E doesn't work when Olaf has activated his ultimate.

Kha'Zix

The mobility and the ultimate from Kha'zix can be very difficult to play against as a Sion!

Warwick

Warwick has a good amount of lifesteal, movement speed and crowd control to be a pain in the *** for a Sion.

Rengar

Exactly the same as with Kha'zix really, the mobility and the ultimate are hard to play against.

Karthus

Karthus is hard to play against when you dont have you ultimate up, because he can kite you easily and also has his E to slow you down which is very anoying when playing Sion!

Ekko

It's hard to play against an Ekko since you never really going to hit a Q, when you Q he will probably dash away with his E, also his ultimate can be very anoying since you're not the fastest jungler around.

Nocturne

Depends on how long the match is going on, Nocturne will probably win early game, but Sion wins the late game!

Trundle

Trundle can block Sion his ultimate by placing his E, also his E can reset Sion his Q.

Amumu

All you need to do is land your Q's which is very anoying for an Amumu to handle with.

Lee Sin

Nunu & Willump

Shyvana

Riven

Riven can reset Sion's Q by knocking him up with her Q, also its hard to play against a Riven since she has a good amount of mobility which Sion doesn't even comes close to.