KarinsDad said:
Only at low level.
At higher level, the Fighter and the Archer full round attack the Wizard and hit virtually every time (due to the low AC of the images) and pop most of the images, or damage the Wizard.
For smart opponents, a Wizard is begging for a stomping if he casts Mirror Image because EVERY opponent should be going after him first instead of allowing him unopposed spell casting, even if that means throwing a dagger at him from a distance. Enemy spell casters should be targeting the Wizard with area affect spells.
As a DM, if your smart NPCs are avoiding the PC Wizard because he is casting Mirror Image, they are being played inferiorly and doing the exact opposite of what they are supposed to be doing. You always take out the biggest threat and a Mirror Imaged arcane spell caster is the biggest threat because he can only be counterspelled or area affected, he cannot effectively be readied against with normal targeted attacks to disrupt his spells or attacked as well straight up.
Your DM is taking it too easy on you. He should be stomping you as the most obvious threat in many battles.
I'm pretty sure you never have played with Mirror Image at low, mid or high levels. I have, a lot.
You should try it some time.
The higher you go, the more powerful actions are. If you cause your enemy to waste actions/attacks on illusions -- that's golden, it can't be beat. The critical that did 75 points of damage -- ooops, it hits an illusion. Mirror Image scales up wonderfully well.
Mirror Image maxes out at 8 images, which is pretty easy to get at mid/high levels. That's 9 total targets.
Let's do a typical 4 on 4. 4 PC's. 4 enemies. 10th level +-2 or so.
Round 1: PC Wizard casts Mirror Image, or had it buffed.
Enemy: durn, that guy has 8 images. He's the big danger. Let's all get him. (yeah right).
NPC1: Archer, hits 4 images (perhaps 3 images and wizard once). 15 damage. Ok ouch.
NPC2: fighter runs up to wizard and hits image. Dispels it.
NPC3: casts an area attack spell vs. wizard. (does some damage)
NPC4: throws 3 daggers and hits the wizard once, dispels 2 more images (ouch).
Great NPC team! You have used up all your actions and attacks, and have suceeded in possibly doing 40 or so damage to the wizard! Meanwhile, the rest of the PC's absolutely rip into you.
And what do we get in round 2?
WizPC: Casts Mirror Image defensively (no roll needed), moves back some allowing the enemy fighter to take an AOO (which hits an image).
Now the NPC's can spend all their time and actions dispelling the images and eventually doing some damage to the wizard - if they are lucky. Meanwhile, the other 3 PC's are busy doing whatever they want: healing the wizard while chopping up the enemy, etc.
Spending NPC time dispelling images is not, and I repeat not, a smart idea. In fact, I would be (and often was) absolutely thrilled if 2 high-powered enemy archers shot 10 arrows in a round and dispelled all the images, and hit my wizard 1ce or 2ce. It won't kill him. He can be healed and more importantly: he can re-cast mirror image. The enemy archers basically wasted 8 arrow shots which might have killed/disabled/etc. another PC in one round.
Carry one! Attack away! You can even do a quickened Mirror Image at level 6 and move and then cast an attack spell. What's not to like?
To repeat: concentrating on the Mirror Imaged PC is giving the rest of the party absolute carte blanche. You can't do enough damage to kill the Mirror Imaged PC in one round unless you are freakily lucky or have the NPC's running True Seeing. So you just do some damage and allow him to re-cast a 2nd level spell.
To put it this way: Is it better to concentrate all your firepower for one round (4 NPC's worth) to dispel figments and possibly do some moderate damage to an enemy wizard or... completely kill the enemy cleric? Or Fighter? Or Rogue?
Your call.
It's tough to kill a dedicated Mirror Imaged mage. Beleive me, I know. I have to try to do it every freakin' week.