Warlock invocations and Metamagic feats

[Almostdead]

We know that
Sudden Metamagic Feats: These metamagic feats don't require modified spell slots, and so they work as well with spell-like abilities or invocations as they do with spells(CAr P.71) and
"Other Metamagic Feats: Except as noted above, metamagic feats can’t generally be used to modify spell-like abilities or invocations." (CAr P.71)
However, the second sentence is quite vague. It leaves some spaces by saying "generally".
In that case, judging by the description of Sudden Metamagic Feats. Can I assume that any metamagic that "don't require modified spell slots" can be apply to invocations?
If that is reasonable, what would happen If I have ways to reduce metamagic cost? Can I apply metamagic with 0 cost to invocations and use them infinitely?

[Almostdead]

Anyone? A little help?

[Ryton]

0 level adjustment metamagic feats seem generally reasonable to add to invocations for free, and the text seems to support it. Energy substitution is nice, but invisible spell might be a little... strange.

What means do you have of reducing costs of metamagic for invocations though?

[skunk3]

I personally think that it would be allowed, but in most cases I don't see the benefit compared to other feats one could take. Most of the sudden metamagic feats are quite limited in use and/or highly situational.

[Silvercrys]

By my reading of the rules, no. Sudden Metamagic feats have a slot adjustment of "-", not +0, and even a +0 adjustment requires you to actually expend a spell slot of that spell's level. As noted on that very same page of Complete Arcane, you can't do this as a Warlock. Spell-like abilities are not spells or spell casting.

But you probably don't break anything by allowing them to be used.

[MisterKaws]

By my reading of the rules, no. Sudden Metamagic feats have a slot adjustment of "-", not +0, and even a +0 adjustment requires you to actually expend a spell slot of that spell's level. As noted on that very same page of Complete Arcane, you can't do this as a Warlock. Spell-like abilities are not spells or spell casting.

But you probably don't break anything by allowing them to be used.

I also read it like that, but apart from obvious level-reduction shenanigans(which break everything tbh), I don't see any problem either.