Well if I'm right about what I'm reading, the increase in spell slots doesn't matter because (for the third time) it doesn't change the spell level
I'm going to target that a moment. I said, "
Intent on prerequisites may still disbar it's usage with Heighten Spell for PrC early entry (actual ability vs capability)"
The 'trick' is say a 1st level Human Warmage, Versatile Spellcaster & Heighten Spell. By merging two 1st level slots he can cast a Magic Missile spell that is treated as being a 2nd level for various effects. This is
capable of casting 1st level spells, however many effects already make you
capable. Scrolls for instance, Wands for another, even certain Races obtain sooner-than-normal SLAs can cast X spell. In a direct example, Precarious Apprentice does grant the capability to cast a 2nd level spell it flat out contains an 'able to cast 2nd level spells' clause for a secondary effect which differentiates between the two, which of course is a "RAW" example that proves otherwise in practice. So there is a high level of tangibility that Prerequisites only refer to the actual abilities in question. Seconded by the fact requirements are not an 'effect' in any context of the rules to which Heighten Spell can say for a fact it influences. But I'm not here to argue that, just explaining things as you seem to getting frustrated.
On the idea of can you use it consecutively? IE four 1st to two 2nds to one 3rd?
That's a no for a few reasons. VS uses two Spell Slots to X-level of Spell and since it does not produce a Spell Slot then you have nothing to work with on that second literation. Inertly, you can only combine Spell Slots and not other sources of spellcasting such as a Ring of Spell Storing or VS's spell fuel conversion. Further this is done on cast and not on preparation so you could not sit down and prepare two 4th level slots as a 5th level slot irregardless if it said it gave you a 5th level slot, meaning you'd have to apply the Feat multiple times at once. And unless noted otherwise Feats do not stack with them selves and even on top of that it names two to one, but not you may repeat NI times or four slots to two to one super big.
And can you use it to pay for Metamagic Costs?
Not directly. Much in the same way a 3rd level Slot cannot be used to help pay for or reduce the cost of an Empowered 2nd level Spell, VS cannot 'reduce' Metamagic costs. It does give the capability of casting a higher level spell which can be used as normal. For instance, Practical Metamagic(empower) reduces Empower from +2 to +1, so you could combine two 1st level Spell Slots to cast a 2nd level spell, this in turn could be used to cast an Empower 1st level spell because in this specific case the Empowered spell is 2nd level, and VS is allowing you to cast a 2nd level spell by way of two 1sts. In the end result you are using two 1sts to cast a normally 3rd level spell, but no you cannot use VS to reduce Metamagic costs, you only change how you're casting the required spell level in question.
Also in closing; You should
never goto GitP if you want to talk about game rules. Ever.
