The tournament rules state:
"615.11. Some effects state that damage “can’t be prevented.” If unpreventable damage would be dealt,
any applicable prevention effects are still applied to it. Those effects won’t prevent any damage, but
any additional effects they have will take place. Existing damage prevention shields won’t be
reduced by damage that can’t be prevented."
Hostility states:
"If a spell you control would deal damage to an opponent, prevent that damage. Put a 3/1 red Elemental Shaman creature token with haste onto the battlefield for each 1 damage prevented this way."
So, if I have Hostility in play and cast a spell which deals unpreventable damage to my opponent (e.g. Banefire), what happens? Is the damage simply dealt without Hostility having an effect (since none was actually prevented), or does the damage get dealt and I also get the token creatures as a result? (since Hostility's other effects are still applied)