If ToV is active can it's 2+ ignore miscast be used as many times as you IF in a single turn? It seems broken doing that but I can't find anything saying that you can't do it.
I don't see why not, also it's a remains in play spell, and it even works if you miscast while casting ToV itself.
Yes, ToV does allow you to ignore multiple miscasts so long as it is active. And if you think that is broken, you will love the next FAQ ruling. Any augment cast while ToV is in effect remains in place even if ToV is removed. As an example, if flesh to stone is cast with ToV and adds +4 T and your opponent dispels ToV afterwards, the +4 T remains in effect - the spell is not downgraded to +2T.
Throw 6 dice while casting ToV, IF get ToV off, roll 2+ ignore miscast. Throw 6 more dice, get Flesh to Stone off, IF, roll a 2+, ignore miscast. (more or less) Also will ToV prevent a Hellheart miscast?
The Hellheart item text says that special rules/items that can affect a normal miscast roll may be used. RAW, some/many Ogre players argue that a roll on the miscast table is not, in fact, an actual miscast, and so will allow Infernal Puppet but not TOV or Cupped Hands. Granted, it's the same logic that many Lizardmen players used to push Cupped Hands past TOV, but still... GW really has to clear up the wording on this kind of thing.
I just went through the FAQ for OK and didn't see anything about the Hellheart in it... so the debate continues.