User blog comment:Alonlah/Who is the best dueler in the game?/@comment-5557556-20140121220109

Simply, Sion.

If you just stand and fight, no running, no tricks, bushes, flashes or other dirty little tricks Sion can kick everyone's ass. He has everything he needs, stun, shield, ad steroid and over the top lifesteal and attack speed.

The problem with Sion comes when you employ dirty tricks against him. Just stall until his ult wears off and he can't duel with you. He also has a very low movement speed so you will be kiting him all day long.