Oh yeah I killed the hag before she even starting combat by just placing barrels around her then detonating them. Instant kill of the hag.
That's my problem in a nutshell - It makes sense in D&D if you're using a bottle of oil or some such, but countless, entire barrels?
Also, the baddies should react to it instead of just standing there pondering which Axe deodorant to wear today while their impending doom literally piles up around them.
I like that the battlefield is interactive, certainly, but within reason and with the interactions prompting responses from its' occupants.
