Hypersmurf said:
Are you sure?
Swarm Attack: Creatures with the swarm subtype don’t make standard melee attacks. Instead, they deal automatic damage to any creature whose space they occupy at the end of their move, with no attack roll needed.
Yes. I considered your quote here when I posted it, but I thought of a way around it. Plus, I like the concept that there is a low level negation spell to Mirror Image (that 4 of the 5 main spell casting classes can get), just like Shield negates Magic Missile or Haste negates Slow.
Your quote here does not state that they "only attack creatures". It effectively states that they "only damage creatures".
"Any successful attack against an image destroys it."
This does not state a successful attack roll, nor does it state that actual damage has to occur. The attack just has to occur.
Swarms can only damage creatures, but they can still attack everything they swarm. They just do not damage everything they swarm.
"In order to attack, it moves into an
opponent's space, which provokes an attack of opportunity."
The images are an opponent. Hence, they
attempt to attack the opponent, they just fail to damage it. It can still be considered a successful attack, just not successful damage. This is similar to when they attempt to attack a creature with DR high enough that their damage does not get through. Successful attack, not successful damage.
The Swarm spells does not "Target: Creature" like many spells.
"You summon a swarm of bats, rats, or spiders (your choice), which attacks all other creatures within its area."
"Enemies attempting to attack you or cast spells at you must select from among indistinguishable targets."
The swarm attempts to attack the caster. They must then select from indistinguishable targets. Now, a given DM might rule that the swarm can only attack "one target" at a time due to literal game mechanics here, but I look at the fact that it is a swarm. It is attacking everything there. It is a cumulative effect of many tiny bites that results in the damage that does occur. But, a literal reading indicates that it is a single attack per round.
I could also see how a literal reading of your quote might prevent a given DM from allowing it (i.e. default thinking = creatures only), but I prefer to use the loophole, just due to the power of Mirror Image.
And even if you do not allow the swarm to auto-destroy all of the images, you should either allow it to auto-hit the caster (like all other creatures in the area of a swarm), or have it either take out an image or damage the caster (depending on the random roll) every round (just like other attacks against the Mirror Image spell). In either case, it is still a fairly effective spell against the defense of a Mirror Image spell.