+hit and periodic resistance checks

[Steamboat]

With spells that have periodic resistance checks (like fear or polymorph - spells that have a chance to break early.) does +hit gear affect the initial cast, or each resistance check as well?

Basically, if you have a bunch of +hit will your fears and polymorphs last longer in general?

[solsting]

I really want to know this too. There are a few different oppinions about this but noone seems to know.

[nespejsen]

hmm, my logic say its penetration, and not +hit that would give better cc, as penetration makes you ignore an amount of resistance on target, if i understand it right..

dont hang me if im wrong, its just thoughts ^^

[Krulle]

+spell hit decreases the chance that the targeted enemy will completely resist your spells (assuming you aren't using a binary spell, in which case spell resistances can cause full resists too). This kind of resistance is level based, i.e. if you shoot a fireball at a mob 4 levels above you, it will have a higher chance of resisting the spell than a mob that is the same level as you are.
On a mob the same level as you, you have a 96% chance to avoid level based resists, assuming no +spell hit gear or talents whatsoever.

After the spell hit chance has been calculated, there's also resistances that determine if the spell is resisted or partially resisted. Binary spells also come into play here, but that's a completely different story ;)

Oh, and +spell penetration basically lowers the amount of spell resistance your target has.

And to answer your question, +penetration would increase the length of cc/any periodic debuffs, since the level based resistance is only checked once for each cast, and that is when the spell lands.