Sinthoraz' (euw top 5 player) ultra high roll comp

So I've been spamming electric with decent success while skipping predators. I usually 3 hyperroll for renekton, ornn and Voli and just crush midgame and pray for zed late.

Sinthoraz runs electric without predators as well and his endgame comp looks something like this

Zed Ornn Voli Nami Yi Twitch Mundo Singed

So this seems very anti meta as it crushes mages and crushes assassin with 3 poison, 2 mystic, 3 electric. He doesn't care for lack of bezerk and preds and he also doesn't go for Voli and ornn 3.

Now, these are awfully many 5 and 4 cost units. I can't find a source in how he survives midgame. Does anyone have a clue? I usually run thresh and naut in my comp and then go assassins so zed completely wrecks people. He seems to get this comp very consistently and it is probably the best late game comp there is.

So does anyone have any ideas on how he does it?