Omniscience

[Maxpayne03]

If I have {Omniscience} on the battlefield, can I cast {Ancestral Vision} without suspense 4 turns?

[Kaylesh]

If I have {Omniscience} on the battlefield, can I cast {Ancestral Vision} without suspense 4 turns?

117.6a: If an unpayable cost is increased by an effect or an additional cost is imposed, the cost is still unpayable. If an alternative cost is applied to an unpayable cost, including an effect that allows a player to cast a spell without paying its mana cost, the alternative cost may be paid.

In other words, you can use {omniscience}s alternative cost to cast {ancestral visions} without suspending it.

[Maxpayne03]

Thanks Kaylesh

[Remillo]

Which is why {snapcaster mage}ing a visions in the graveyard is so good. 

THAT doesn't work.  Snapcaster gives it a Flashback cost equal to it's mana cost, so...  A nonexistant one that can't be paid.  If it gave it a cost equal to it's CONVERTED mana cost, it'd be 0.