remember when they updated singed and voli flips to not be bullshit, years ago?

how come urgot e can't be buffer jumped? it seems so random. 2 games in a row, i'm playing ezreal against urgot. first i get planted right in front of a thresh hook after buffer jumping an urgot's flash-e, then i get planted under turret through buffer jumping urgot e after a lane swap. why does it count as 2 different CC effects? why does only the initial "stun" get canceled by buffer jumping?