Mirror Image (Cooldown 15 Seconds): You summon two illusory duplicates of yourself that last 7 seconds or until destroyed. These duplicates have 25% of your Life, the same defenses as you, and your set of skills. Their attacks and skills deal no damage, but draw attention as though they did the same amount of damage as yours.
Mirror Image is a quirky defensive spell for several reasons. The images follow you fairly closely, for one, so they’re not very good at drawing enemies away from your location. The images draw aggression as though they were dealing damage, despite the fact that they can’t deal any. And, most interestingly, Mirror Image doesn’t play nice with Fracture. Using Fracture will destroy any remaining dupes created by Mirror Image, and using Mirror Image will destroy the Fracture decoys. This wouldn’t be so bad if not for the fact that the Fracture decoys don’t attack at all, though they do borrow some of your aggro.
Simulacrum (Cooldown 15 Seconds): You summon two illusory duplicates of yourself that last 7 seconds or until destroyed. These duplicates have the same Life and defenses as you, and your set of skills. Their attacks and skills deal no damage, but draw attention as though they did the same amount of damage as yours.
If you find that your Mirror Images die too quickly, then Simulacrum will keep them up and running for most if not all of the full 7 seconds they can last. This is a good way to essentially boost your Life pool and survive a little while longer- since the dupes don’t move away from you, don’t rely on this to fully occupy enemies or stop them from hurting you at all. Even at its best like this, the reprieve is temporary.
Duplicates (Cooldown 15 Seconds): You summon five illusory duplicates of yourself that last 7 seconds or until destroyed. These duplicates have 25% of your Life, the same defenses as you, and your set of skills. Their attacks and skills deal no damage, but draw attention as though they did the same amount of damage as yours.
Another way to cause more confusion and get more duration out of Mirror Image, Duplicates is a different tradeoff from Simulacrum. Duplicates is a lot more useful when you are facing enemies who attack powerfully but slowly, where Simulacrum has more overall durability and should be used to deal with numerous weaker enemies.
Mocking Demise (Cooldown 15 Seconds): You summon two illusory duplicates of yourself that last 7 seconds or until destroyed. These duplicates have 25% of your Life, the same defenses as you, and your set of skills. Their attacks and skills deal no damage, but draw attention as though they did the same amount of damage as yours. When they die, the duplicates explode, dealing 45% weapon damage as Physical damage to all enemies in melee range with a 50% chance to Stun each enemy hit for 2 seconds.
The best way to deal with an onslaught of melee attackers is to stop them from attacking you. If you’re facing a large number of minions that bash you around, Mocking Demise will hold them off for less time than Simulacrum- but it will in turn stun a good portion of them. Because of this it is slightly less defensive- use Mocking Demise to stop enemies from attacking you so you can buy yourself time to blow them up in response.
Extension of Will (Cooldown 15 Seconds): You summon two illusory duplicates of yourself that last 10 seconds or until destroyed. These duplicates have 29% of your Life, the same defenses as you, and your set of skills. Their attacks and skills deal no damage, but draw attention as though they did the same amount of damage as yours.
If you’re more concerned with extending the maximum duration of your Mirror Images, because they vanish before they die, Extension of Will is your rune. Don’t rely on the increased Life total of these things- 4% isn’t much at any level. If you use Mirror Image frequently, then they’re probably taking too much damage for the duration boost to matter. If you only use it occasionally and it spends most of its time waiting for you to trigger it, though, then this rune should be considered.
Mirror Mimics (Cooldown 15 Seconds): You summon two illusory duplicates of yourself that last 7 seconds or until destroyed. These duplicates have 25% of your Life, the same defenses as you, and your set of skills. Their attacks and skills deal 10% of the damage yours do, but draw attention as though they did the same amount of damage as yours.
If you want to try to use Mirror Image to boost your offense, an alternative to Mocking Demise is Mirror Mimics. This is most useful if your attacks rely heavily on side effects like slowing, stunning, chilling, or knockback, as it improves the frequency of those happening far more than it boosts your damage. Of course, it still operates defensively just fine, so if you’re okay with the duration and durability of the base Mirror Image, then you should probably default to this rune rather than any of the others.