[evileeyore]

Originally Posted by Tom H.

Was this actually the intent, is it usually played this way, how are the complications that I presented addressed?

They weren't. most of it falls under 'common sense', but I know Kromm has weighed in a few times so my take on it is influenced heavily by those old posts (which I don't have time to hunt for, they might be in the UFAQ).




I know it's "magic," but I would at least welcome a bit of rigor on the physics of it.

There are two issues to be addressed.

1. Is it too powerful that a simple area effect can penetrate a two foot thick iron wall enclosing a volatile substance as easily as something less invasive such as flowing around an obstacle on an open field.

What volatile substance? If isn't 'air' the area effect won't manifest.

2. What are the physics (and playability) of protecting gear, potions, and the inside of your skull when engulfed in an area effect if a two foot iron barrier is negligible.

Stop thinking about 'barriers' as barriers'. They are things the magical affect can't materialize within. Same goes for containers, stomachs, etc. My rule of thumb is "if the 'contained' space is too small for an SM 0 creature to fit into, it's too small for magical effects". I know, this can lead to nitpicking, I reward nitpicking with a rolled up rulebook to the head until the nitpickers stop.

Basically, thin hallways? Fill with area effect. Chest, pouches, containers? Do not.

Maybe the magic knows the difference between a Fairy's crawlway and scroll cubby hole.

What density of matter is considered low enough for displacement by the area of effect: air but not liquid or grey matter?

There is no displacement. The effect and the air (or void) exist simultaneously.

Are biological barriers magically resistant? It can't bypass my stomach or chest?

It can if you breathe it in or swallow it.

Does the effect only manifest within certain sizes of enclosure precluding flasks and scroll cases?

See above "containers' versus 'hallways'.

Things powered by GURPS are usually known for exploring these questions.

Magic (the book) never really bothered. These forums have, but the books don't.

It usually boils down to 'what do you and your Players think is fun".

If I recall correctly, their magical area effects initiated at a singular point and emanated outward by flowing around obstacles. This provides a degree of "physics" that allows you to reason about the issues I presented.

If that's how you want to play it. The rules as presented in Magic (and DFRPG Spells) don't do it that way. The area effect spell materializes in all areas it covers at once. It doesn't "fill" or 'flow' or overpressure and deal extra damage because you tried to fit a 10 hex Fire Cloud into a 5 hex room.


And your Smoke cloud doesn't back pressure and then flow back down the corridor and engulf your own party! I'm looking at you GM!*



* My GM does this with spells sometimes, but it's spells cast from a Psionicist's enchanted staff, so weirdness.