The feat doesn't come with prerequisites but the benefit text heavily implies that spell combat would be one.
I would assume you couldn't pick that up with VMC 7th level Magus Arcana ability. But just to be clear.
Also just for kicks. For a Charda it would be 4 attacks (3 claws 1 bite) at -2 and a spell
It is a Magus Arcana, not a Feat.
You aren’t technically required to have Spell Combat to select it, but i can’t imagine why you would want to do that since it would be useless if you didn’t have Spell Combat.
To use 3 claws and 1 bite while casting a Spell you would need to select the Arcana at least 3 times and have the Spell Combat Class Feature.
Wouldn't it be twice?
Once for claws and once for bite?
For example, a magus could select this arcana twice, choosing claw attacks and bite attacks. This would allow him to use a full-round action to make all of his claw attacks with his free hand and all of his bite attacks in addition to casting a spell. This arcana otherwise functions exactly like the spell combat class feature
Yeah, I kind of guessed that it would be useless without spell combat.
Based upon the wording of Natural Spell Combat, I think you only have to select it for each different natural attack, not once for each natural attack of the same type. Also, this FAQ makes it look like you don't need it at all for claws on your hands, even though the text of Natural Spell Combat gives claws as an example (this would be needed if you had claws on your feet and had Pounce + Rake, for example).
Edit: Actually thought of 1+1/2 situations in which the Natural Spell Combat Magus Arcana could be useful with VMC Magus (although VMC Magus itself wouldn't be, due to duplicating abilities of the primary class): Phantom Blade Spiritualist (which has its own Spell Combat, but also has its own Spellstrike), and arguably Ectoplasmatist Spiritualist, which has its own Spell Combat but with enough differences in description that it might not be accepted as qualifying for modification by Magus Arcana (including effectively being integrated with a type of Spellstrike).