I hate Kassadin more than the average guy (I like to play mages), but here's a cool SR tournament story:
I was watching OGN early this morning Xenics United was playing against NaJin. CoCo, Xenics' mid-laner, was playing my buddy Kassadin. He went 21/0/8 and crushed the enemy team so hard. The other lanes weren't losing, but then they were all carried by this teleport Kassadin. He was all over the map and then teleported to be all over another lane. He built RoA > Tear > Manamune > DFG > GA > Void Staff. Not even Maknoon's Rumble, who was teamfighting well even with his poor ult placements, couldn't handle it. I was laughing at how much damage and CC was coming out of that champ on Summoner's Rift.
Xenics comp: Kassadin, Xin Zhao, Renekton, Ezreal, Lulu.
NaJin's comp: Twisted Fate, Nocturne, Rumble, Miss Fortune, Leona.
AND since we all know that it takes a SR team to play a champ before it gets a nerf (see: Jayce, Kha'Zix, Rengar, Lulu, Urgot), here's to hoping more people start playing it on SR and RiotNome's job will be easier as the main team can nerf his OPness.