Real good spell.

So do your duplicates copy spells you cast? And do they do damage or are they just imitations?

Just imitations 

Just imitations, yes.  But, I would also argue, mimics the image of your spells so as to disguise your location; so you don't give yourself away casting magic missile or something.

Right. They copy your movements exactly, including somatic components. They are completely indistinguishable.

My DM is saying that creatures with Tremorsense shouldn't be affected by this spell, but everywhere else I look online people say that the Tremorsense isn't SO accurate that it can pinpoint you, and differentiate you from your duplicates. Thoughts?

Why not just close your eyes and attack as if blinded with disadvantage instead of attacking with a one in four chance of getting the right one?

What happens if you go down? My DM said that the images would not persist, and I agree with that because that makes sense. But it says that the spell ends when you dismiss it, all illusions are destroyed, or you dismiss them as an action. Since it's not concentration, that leads me to believe that the ruling would be that the illusions stay.

For example: if you cast sleep, the enemies wouldn't be triggered to wake up if your character goes down.

But it doesn't make sense for the illusions to still be there if you've gone down. It would still benefit you and possibly prevent a death saving throw. Thoughts?

Yeah, the illusions would stay even if you are incapacitated, asleep, paralyzed, petrified, or whatever.

"Oh no, HailRobonia the illusionist is down, someone heal him!"

"I'm trying, but I keep healing his mirror images!"

If the attacker is wise or intelligent enough to realize a viable strategy against this spell is closing their eyes and relying on their other senses to attack, I'd give it to them. Having your attacker hit you with disadvantage is comparable to the other 2nd level illusion spell, Blur. Also, because the blinded target would be unaffected by the spell, I'd rule that the duplicates stay in place for any other attacker using sight.

The problem with this is that you are not only attacking with disadvantage, but now opening yourself to being attacked by anyone else and giving them advantage on that attack, not just the one you're attacking that has mirror image up. Someone else compared it to the spell Blur but I actually consider this spell stronger for the above reason. I as a DM would let you close your eyes but be aware that for the next round all attacks against you will be with advantage. 

TLDR: it's a strong spell.

No concentration,

Would someone be able to know which one is the real on with investigation?

If an attack hits a duplicate, the duplicate is destroyed. A duplicate can be destroyed only by an attack that hits it. It ignores all other damage and effects.  

Does this mean AoE attacks can destroy multiple duplicates, or that they can only be destroyed by attacks requiring attack rolls?

Quote from CoagulantLyric >>

If an attack hits a duplicate, the duplicate is destroyed. A duplicate can be destroyed only by an attack that hits it. It ignores all other damage and effects.  

Does this mean AoE attacks can destroy multiple duplicates, or that they can only be destroyed by attacks requiring attack rolls?

 
What is an "area of effect attack?" I understand what you're getting at, but there's no such thing in the game. For example, a Fireball isn't an "attack;" it's an effect that does damage in a designated area.

As it states in the spell description, the wizard must be the target of the attack: that is, the attack must be able to select the wizard as the target and then must make an attack roll.

Fireball, for example, will damage the real wizard. The mirror images will still be present, now looking slightly cooked, just like the wizard.

Quote from CoagulantLyric >>

If an attack hits a duplicate, the duplicate is destroyed. A duplicate can be destroyed only by an attack that hits it. It ignores all other damage and effects.  

Does this mean AoE attacks can destroy multiple duplicates, or that they can only be destroyed by attacks requiring attack rolls?

You have to use effects which hit a specific target.

So, unfortunately you couldn’t use fireball to mop them up immediately (although, you might be able to make some progress with Magic Missile).

Quote from Dr_Frederick >>

Quote from CoagulantLyric >>

If an attack hits a duplicate, the duplicate is destroyed. A duplicate can be destroyed only by an attack that hits it. It ignores all other damage and effects.  

Does this mean AoE attacks can destroy multiple duplicates, or that they can only be destroyed by attacks requiring attack rolls?

 

You have to use effects which hit a specific target.

So, unfortunately you couldn’t use fireball to mop them up immediately (although, you might be able to make some progress with Magic Missile).

This is relatively viable. You can't directly target a duplicate, you can only target the caster. The four figures occupy the same space, so you might not even see all four at once. For each missile, the caster then rolls to see whether the missile hits them or one of the dupes, adjusting the roll each time a dupe is hit. There's a strong chance you'd take out all three duplicates in one shot. With second level Magic Missile, you'd have a near certainty of taking out all the dupes and also dealing damage to the caster.

 "the duplicates move with you and mimic your actions, shifting position so it's impossible to track which image is real."

Does this mean that any image can get closer to the enemy, away from the enemy, or flank? I am confused on how a person who casts this spell, how can they position them. Also HOW FAR can they be apart from each other.. That isn't specified lol

a couple of months late so i doubt its an issue any more, but in the rules of the spell it mentions that a creature would be unaffected if they rely on senses other than sight. so i would rule with him that because tremorsense allows you to feel where people are, it would not affect that creature. the illusions do not have weight to them. 

Quote from SkyScraperC >>

My DM is saying that creatures with Tremorsense shouldn't be affected by this spell, but everywhere else I look online people say that the Tremorsense isn't SO accurate that it can pinpoint you, and differentiate you from your duplicates. Thoughts?

 a couple of months late so i doubt its an issue any more, but in the rules of the spell it mentions that a creature would be unaffected if they rely on senses other than sight. so i would rule with him that because tremorsense allows you to feel where people are, it would not affect that creature. the illusions do not have weight to them.