Volcanic Fallout can be targeted by spells that try to counter it (such as Countersquall). Those spells will still resolve, but the part of their effect that would counter Volcanic Fallout won't do anything. Any other effects those spells have will work as normal.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.