This may depend on the spell. Invis may turn you incorporeal(relative to which plane you left/are on) with full situational awareness, and in order to attack something, you may need to break the spell(s), returning you to the "prime material plane" before you engage.Windemere wrote:Part of the problem here is that a variety of other mechanisms for bypassing/getting around certain things have been removed.
3. Invisibility does not mean you are non-corporeal. You still have a body, you have just shifted yourself to a plane where you cannot be seen. If you want to argue you are in "another realm" when invisible, that is fine, but there should be some ramifications that come with that. I.E. not being able to attack from within this "other realm". If you are still in the same "realm" then your body should behave like any other body. There would then be risk that you can't just walk past the orcs because you'd bump into them. They could still smell you? Feel your presence? There are numerous reasons why an NPC could block/stop an invis character and if we go by what has been done in the past with Darkness/Stealth, then the changes make sense to limit abuse and fit more within the realm of what makes sense.
Windemere
So, if you are invisible and incorporeal, you may pass through physical objects with no issues, or, if you have similar restrictions like the classic d&d wraithformspell, you only need a physical opening (as in, not airtight) to enter/pass unnoticed.
In fantasy, many angles how invis, or invis + secondary and tertiary spells may function without restricting them to full physical bodies.