Omniscience: Why?

[CbStrad]

So, {Omniscience} has so much potential to cause so much rage. My question, though: could it be playable outside of Casual? Now, I can see it being super-sexy in a Blue Eldrazi deck ("Yeah, I'll just drop Omni with a few Spawns and Islands. 'Drazi gods for free. Oh, and it's only turn 4"), MAYBE a Simic deck with enough ramp. Otherwise, I'm not seeing much use for a 10-cost Enchantment; with the current meta, 10 mana is usually enough to play all you need as-is.

[Dudecore]

Legacy: {Show and Tell}. Pretty common occurrence

[Kaleo42]

A guy went 4-1 with a deck centered around this card two weeks ago. It was green blue control. He had {garruk, primal hunter}, {tamiyo, the moon sage}, tons of mana dorks, and multiple {craterhoof behemoth}s for the kill. The deck functioned well with or without {omniscience}, but thanks to the synergy of his planeswalkers with te dorks and a few {wolfir silverheart} he always had cards to cast when he dropped the enchantment turn 5,6, or 7. Oh and did i forget to mention {temporak mastery} performed AMAZING in this deck early, mid, and late game.