Galiois pretty effective as an assassin counter... I have heard stories of people using him as their Yasuo counter. His natural tankiness means he can shrug off the attacks of most assassins... Winds of War (his Q) is an effective ranged small radius AoE attack... Perfect for hitting Akali in her shroud for example. His W (Shield of Durand) not only provides extra tankiness from the shield, but the second cast is a taunt, which effectively stops most melee assassins (and interrupts channeled abilities like Katarina's Death Lotus). His E (Justice Punch) provides some additional Crowd Control and works as a gap closer. Finally, his R (Hero's Entrance) allows him to partially keep up with a roaming enemy assassin and provide chances to save an ally who gets ganked.
Kassadin - This champion has a lot of good counters hopefully. He has only 41.8% winrate against Wukong and then he is quite bad into champions like Talon, Nocturne, Qiyana, Renekton and Galio. Against those 5 champions, Kassadins winrate is not higher then 47%.
Talon - Pretty bad into Pyke - only 45.9% winrate... other champions like Wukong, Neeko, Katarina are also solid counterpicks but it makes Talon's winrate only slightly below 50%
Katarina - Pretty hard to counter. Against Fizz she has 48.7% winrate, everything else is just irelevant.
Alternatively, Pantheon works fairly well against assassins as well. He has point-and-click CC with Shield Vault, the ability to negate the biggest part of all-ins with Aegis Assault and he can follow up on roams with Grand Starfall.
Well I hope I clarified most of the assassin matchups feel free to ask If I missed some. Have a good day <3
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