Post/Author/DateTime	Post
#1 FrogReaver Mar 01, 2015 23:05:06	Mirror Image -  Each time a creature targets you with an attack during the spell’s duration, roll a d20 to determine whether the attack instead targets one o f your duplicates.  If you have three duplicates, you must roll a 6 or higher to change the attack’s target to a duplicate. With two duplicates, you must roll an 8 or higher. With one duplicate, you must roll an 11 or higher.  A duplicate’s AC equals 10 + your Dexterity modifier.  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. The spell ends when all three duplicates are destroyed.     I'm trying to come up with a good way to determine it's effectiveness.  Any ideas?
#2 FrogReaver Mar 01, 2015 23:17:46	These are not true calculations but for example if out of 6-8 attacks it got a 90% chance of deflecting 3 of them I'd consider that a fairly strong spell.  The ability to turn about half of the first attacks 6-8 attacks during combat into doing nothing seems fairly good to me.   I'm not sure if that comes out anywhere near it's actual strength though
#3 Archon007 Mar 01, 2015 23:41:31	It's random. Statics will tell you on average it will do x over a million rolls but reality is the casters is facing a tiny sample size of rolls. I cast it and out of 3 hits on 5 attacks all 3 hits, hit the caster and he went down and lost the spell. Overall it's a good spell but what I'm trying to say is its random and you can be lucky or unlucky with it.
#4 EmpactWB Mar 02, 2015 0:15:54	.75 chance to target a duplicate, .5 chance to hit said duplicate and destroy it, .375 chance for the first duplicate to take one for the team from any given attack it is present for. The first duplicate lasts fewer than three attacks on average, but on average will prevent most of those attacks from targeting you.   .65 chance to target a duplicate, .5 chance to hit, .325 chance for the second duplicate. The second duplicate lasts just over three attacks on average, and keeps just under two of them off you on average.   .5 chance to target, .5 chance to hit, .25 chance for the last duplicate. The final duplicate lasts four attacks on average, keeping two off you.   So, on average, the spell prevent 6-7 attacks from targeting you. Archon007 may be right about individual results varying, but it's still pretty nice from my perspective.
#5 Byakugan01 Mar 02, 2015 2:56:18	I use mirror image frequently with my 5th level wizard.    I use a judgment call as soon as i figure out if the fight is minions or dangerous stuff.     The DM likes attacking me, so even with smart positioning i usually end up with monsters in my face.     Its pretty good, but most things have multiattack at our level. i can usually avoid the scary brutish things since the meat shields tend to engage fast.    My experience is that against average encounters where the odds if getting a monster in your face it prevents about 5-10 damage per image, and usually 2 images get hit before i get hit the first time. If you get through all 3 images, you might have effectively doubled your HP.    Against anything that piles on dice from things like poison or rend its amazingly good.
#6 CFK Mar 02, 2015 7:26:30	Don't have my book on hand, but ever thought of casting mirror image when blurred (with the blur spell)? (can't be sure, but in my recollection, one of them is with concentration and the other isn't... right?)   And mirror image is all about chance. The enemy has a chance NOT to hit you greater then to hit you. IMHO it's better than having an armour bonus: The enemy needs to hit the right image AND hit with an attack. Mirror image even has the ability to let the enemy "miss" on a crit... think about it.
#7 mellored Mar 02, 2015 7:56:34	Short answer.  It will stop 3 hits.  Misses don't matter, since an enemy rolling a 1 wouldn't hit you anyways.   Medium Answer: 1/70% + 1/60% + 1/50% = 5.0952380952380952380952380952381 It stops 3 of the first 5 hits.  (on average).     Long Answer: The effective AC difference between you and your duplicate changes it's effectiveness. If you have more AC (mage armor, blurr, shield) then there's a chance that an attack that would of missed you anyway, but still hits the duplicate, thereby "wasting" a duplicate. If you have lower AC (reckless attack), then there's a chance that an attack would miss your duplicate when it would of hit you.  Prevening 1 addional hit. Mirror image can also prevents crits.
#8 mellored Mar 02, 2015 8:11:49	Blurr is better if you have high AC and/or take more (~6) attacks.   Though concentration kinda keeps it down too.
(Reply to #8) FrogReaver	mellored wrote:
#10 Mommy_was_an_Orc Mar 02, 2015 8:28:22	It is a bad spell unless you have prep time or no other way of getting a spell off for some reason. Or your DM takes spellcasting to mean 'attack that target regardless of spell cast'
#11 mellored Mar 02, 2015 8:33:25	FrogReaver wrote:
(Reply to #11) FrogReaver	mellored wrote:
(Reply to #10) FrogReaver	Mommy_was_an_Orc wrote:
#14 mellored Mar 02, 2015 8:36:36	FrogReaver wrote:
(Reply to #14) FrogReaver	mellored wrote:
#16 mellored Mar 02, 2015 9:02:21	FrogReaver wrote:
#17 Clutchbone Mar 02, 2015 9:46:40	You can use mirror image and suggestion/hold monster/fear etc. at the same time.   You cannot with blur.   That's enough for me to make a decision.     Doesn't blur also gets worse vs high damage enemies because of the higher Concentration check? It seems that concentration checks would be a major factor in determining blur's usefulness.
#18 Mommy_was_an_Orc Mar 02, 2015 9:52:28	FrogReaver wrote:
(Reply to #16) FrogReaver	Concentration can fail too. Even with the basic 10 check if not careful.  Especially before the last couple of proficiency bonus bumps.     It doesn't take long for even a 5 percent chance of failure on every hit to snowball into losing concentration.   mellored wrote:
(Reply to #18) FrogReaver	Isnt web web a concentration spell?   Mommy_was_an_Orc wrote:
(Reply to #17) FrogReaver	Good point on concentration.   Clutchbone wrote:
#22 FrogReaver Mar 02, 2015 22:54:01	By my estimates: ***All calculations assume you have the same AC as your mirror image.  If your AC is higher than the mirror images then there becomes a chance of images being wasted on attacks that would have normally hit you.  This is not factored into the calculations below.    If a monster had a 100% chance to hit you then the mirror image spell has about a 90% chance of causing 3 attacks to miss by the time you take 7 attacks. Out of those 7 attacks you will take about 4 hits instead of your normal 7.   If a monster has a 50% chance to hit you then the mirror image spells has about a 90% chance of causing 3 attacks to miss by the time you take 16 attacks. Out of those 16 attacks you will take about 5 hits instea of your normal 8.     3/7 = 42.8% 3/8 = 37.5%   I would estimate that mirror image provides around 30-40% damage reduction against 16 attacks at 50% chance to be hit and also against 7 attacks at 100% to be hit.  If there are far fewer attacks than expected then it's effective damage reduction can climb as high as 75%.  If there are far more attacks than expected then it's effectiveness can drop off.  If the chance to hit changes then number of attacks can be adjusted accordingly and will stay around the 30% - 40% damage reduction value.     **Note that estimates were obtained by using averages in the binomial probability distribution and our probability distribution isn't binomial (though it is close).     My conclusion is that it's an undervalued defensive spell for a lower AC wizard and also an undervalued defensive spell for many front line fighters.  IMO it's pretty comparable in strength to blur and doesn't require concentration.  Don't get me wrong, blur is a little stronger in effect but it does take up your concentration slot and mirror image does not.   Of course there are times to not consider mirror image 1.  If your AC is much greater than what the AC of your mirror images would be.  In other words any character that has a higher AC and not much dex. 2.  Certain enemies are not affected by mirror image   Then again we can make an obvious list of reasons for times not to consider blur as well 1.  Low con saves and planning on being in melee 2.  Want to keep options for other concentration spells open
#23 CFK Mar 02, 2015 23:14:50	And yet I was wondering on this subject last night.   I always liked the character Rinzwind from the discworld series by Terry Pratchett and one of his "life lessons" was: If your to close to an enemy that he (or she) can hit you, your TO CLOSE! Cast Mirror Image and GTFO of range, hide behind the half-orc barbie and let him/her fight it out...   The OA has a smaller chance of hitting and your safe to hide/run/make fun of fighters another day. Colour Spray works better, but it can hit your friends to...
#24 Mommy_was_an_Orc Mar 03, 2015 9:04:35	CFK wrote:
(Reply to #10) Clutchbone	Mommy_was_an_Orc wrote:
(Reply to #24) FrogReaver	And yet an alive wizard or fighter does more damage than a dead or unconscious one...   Dilemmas indeed!   Mommy_was_an_Orc wrote: