Originally Posted by
4eak
Volcanic Fallout is obviously good against blue-based aggro decks. Merfolk in particular, Counterslivers (depends) and Faeries (flyers, so Fallout is obviously better) as well. For most everything else I prefer Flamebreak. Against Lord-based decks, it may require an additional burn spell to clear the field though.
The instant speed could be decent against Ichorid tokens, which are often generated en masse on their fundamental turn (leaving no time to answer at Flamebreak's sorcery speed). If it doesn't get therapy'd away, then it could timewalk you several turns, perhaps even just win on its own if they expended too many resources to roll you. Alongside bridge-removal through Fanatic/Marauders, Fallout wouldn't be awful.
I also like the card against Landstill decks which abuse Elspeth (admittedly, itself answered by our targeted burn) or DoJ. If you can handle their win conditions, then slow-rolling them becomes even easier.
As you said, it seems like a reasonable maindeck choice for an especially metagamed burn deck. I could also see Fallout easily justified in the side for burn in general.
peace,
4eak