# Mirror Image Math

#### FrogReaver

##### Legend
Blur definitely gets better for someone like a Bladesinger with Warcaster. Even with a 13 con and 16 int, my Bladesinger almost never loses concentration.
Does it? That's the premise for creating this thread. How many attacks do you have to take before blur starts being better than mirror image?

For example - say an enemy has a 50% chance to hit you. I'll even be generous and assume it never breaks your concentration.

Until the enemies have attacked you enough to kill all the mirror images on average then mirror image provides more protection than blur. They don't provide quite as much crit protection though - but still provide significant protection there as well.

The question is how fast will the mirror images go away? Not super quickly even in this scenario because they would have a high chance to be hit when targeted, but not 100%. They probably last you through 7-8 attacks on average.

In short - you might be overvaluing blur compared to mirror image in many circumstances.

Mirror Image, OTOH, relies less on anything other than the spell itself to protect you. Not something that is easy to quantify, but certainly a benefit.
It also cannot be removed by failing a concentration roll.

#### FrogReaver

##### Legend
I don’t think that really requires much intelligence. The magic guy just made himself into 4 people, and it’s hard to tell what’s real. I hit slow and big, and the guy with the shield is just standing there.

Maybe the enemies aren't so bright and think all those are real people and start targeting that blob of wizards more.

#### Saelorn

##### Hero
likewise you should never assume the enemy has a clue.
Without making any assumptions, we don't have enough data to speculate at all. The assumption of competent enemies will better reflect the conditions in the game where you would need a defensive buff.

#### FrogReaver

##### Legend
Without making any assumptions, we don't have enough data to speculate at all. The assumption of competent enemies will better reflect the conditions in the game where you would need a defensive buff.
Your games run quite a bit different than mine.

#### Stoutstien

##### lunk
While going through my notes and trying to get this into a single formula with advantage/disadvantage, I realize that there is another difference between blur and mirror image that might come up. Grappling. As far as I can tell if somebody attempts to grapple/shove somebody who is under the effect of blur it doesn't interfere with it. so if they are pushed prone it could potentially work around the spells effects where mirror image is based on target selection and the duplicates are immune to grapple/shove.

#### Blue

##### Ravenous Bugblatter Beast of Traal
Your games run quite a bit different than mine.
I think that if they see one person, and then suddenly in the same area are four identical people, all moving exactly in sync and swapping psoitions around (both as per the spell description, so obvious in game), I would think even an ogre's low intelligence might be able to go "oh, magic".

##### Heretic of The Seventh Circle
Maybe the enemies aren't so bright and think all those are real people and start targeting that blob of wizards more.
Sure, maybe. I don’t really care either way, I’m just saying, it doesn’t require tactical genius to avoid using attacks against the wizard.

##### Heretic of The Seventh Circle
Does it? That's the premise for creating this thread. How many attacks do you have to take before blur starts being better than mirror image?

For example - say an enemy has a 50% chance to hit you. I'll even be generous and assume it never breaks your concentration.

Until the enemies have attacked you enough to kill all the mirror images on average then mirror image provides more protection than blur. They don't provide quite as much crit protection though - but still provide significant protection there as well.

The question is how fast will the mirror images go away? Not super quickly even in this scenario because they would have a high chance to be hit when targeted, but not 100%. They probably last you through 7-8 attacks on average.

In short - you might be overvaluing blur compared to mirror image in many circumstances.
I’m not valuing blur at any particular level of value. I simply stated that blur benefits the caster more they more they have an unstoppable concentration, and the higher their AC, while mirror image benefits the caster the same regardless, for the most part.

to really make sure it’s clear, let me put this explicitly, I never said blur is better than mirror image in a given context, I said that blur is better in some contexts than it is in others.

It also cannot be removed by failing a concentration roll.
Yep. Thought I had included that in my post, so good catch.