Ojutai EDH Control

Detention Sphere is probably going to be better than Oblivion Ring for that type of effect just because it does everything O-Ring does but can also on occasion hit a swarm of tokens, or take out an Avacyn and the copy someone made of Avacyn, etc.

It's probably also not going to matter much, but Void Shatter has the same cmc as Cancel plus it exiles the spell, plus it can't be hit by the occasional Red Elemental Blast you see in a mono-red deck. If Void Shatter was a three dollar card I'd say who cares for the 1 in 100 games where it matters, but since it's like a twenty cent card there's really no reason not to switch.

Myriad Landscape and Wayfarer's Bauble are one of the few ways you can land ramp in W/U. I'd consider both. Also since you have plenty of draw I'd consider finding a slot for Terrain Generator. I've never been unhappy to see it in my W/U sphinx deck.

I've been having great luck with Overwhelming Intellect lately. The trick is to not think of it as a counterspell; it's a terrible counterspell to need to use to save yourself. The trick is to think of it as a draw spell that also sets your opponent back a card and mana. If you're holding six mana open for it hoping to save yourself from something you'll always get burned, but if you hold six mana open because you looked around the table and saw that at least one of the other people was gonna try to cast a creature next go around (which is almost every single round) then you can just think of it like a Blue Sun Zenith that ruins their turn and fills your hand.