Diablo III- Skills Article CXXXVI: The Wizard, Defensive Skills- Diamond Skin

Diamond Skin (Cooldown 12 Seconds): Your body is covered with a layer of diamonds that lasts until it absorbs an amount of damage based on your level (10853 at level 60) or six seconds elapse, whichever comes first.

Diamond Skin is a very nice defensive skill for Wizards who want to be able to stand their ground- so close range Wizards should take note.  It’s worth noting that the skill depends on your level only, so once you reach level 60 it will start gradually getting worse.  This is alleviated somewhat by improvements in gear, but not enough to ensure that it stays relevant at all times.  Consider swapping it for something else in the lategame.  That said, the six-second duration is wonderful, letting you stay in Diamond Skin half of the time as long as you remember to trigger it when it comes up.

Crystal Shell (Cooldown 12 Seconds): Your body is covered with a layer of diamonds that lasts until it absorbs an amount of damage based on your level (21707 at level 60) or six seconds elapse, whichever comes first.

By doubling the damage capacity of Diamond Skin, Crystal Shell lets you endure even boss fights in melee range or damage zones for much of its maximum duration.  If you find that your Diamond Skin often breaks before its time runs out, this is a good rune to pick up.  As with the base skill, you’ll slowly outgrow it after level 60, so look into a replacement around that time.

Prism (Cooldown 12 Seconds): Your body is covered with a layer of diamonds that lasts until it absorbs an amount of damage based on your level (10853 at level 60) or six seconds elapse, whichever comes first.  The cost (or per-second cost) of all your Arcane Power consuming skills is reduced by 7 while Prism is active.

For those who need to continue dumping their Arcane Power while their protection is active, Prism is a great way to boost your efficiency and durability at the same time.  While this isn’t as nice as improving its defensive aspect, it will still keep you on your feet during a vital time, and used in the middle of emptying your Arcane Power pool can let you dish out tons of extra damage in a pinch.  In situations where you only need one of those two effects (improved defense and improved efficiency), it’s strictly inferior, though.

Mirror Skin (Cooldown 12 Seconds): Your body is covered with a layer of diamonds that lasts until it absorbs an amount of damage based on your level (10853 at level 60) or six seconds elapse, whichever comes first.  When an attack’s damage is absorbed by Mirror Skin, it deals half the absorbed damage back to the attacker.

Mirror Skin is a cool idea that sadly is ineffective by the time it becomes available, and quickly becomes even worse.  The sheer amount of Life possessed by higher-end monsters and the reliance of most classes on damage reduction rather than massive Life pools means that the retributive damage is simply not enough to be worth noticing, making only a tiny fraction of the damage a Wizard can pump out with more actively offensive skills.  Chances are you won’t want to use this.

Enduring Skin (Cooldown 12 Seconds): Your body is covered with a layer of diamonds that lasts until it absorbs an amount of damage based on your level (10853 at level 60) or eight seconds elapse, whichever comes first.

By protracting the duration of Diamond Skin, Enduring Skin is supposed to stay active longer.  Unfortunately, the way damage scales and the amount of damage incoming means that your Enduring Skin usually will be overloaded before six seconds pass, nevermind eight, so this rune isn’t really all that great.  If you like to trigger Diamond Skin before running into combat, though, and see it sometimes run out before you really start taking hits, you might want this- but most of the time you need more damage absorption, not more time.

Diamond Shards (Cooldown 12 Seconds): Your body is covered with a layer of diamonds that lasts until it absorbs an amount of damage based on your level (10853 at level 60) or six seconds elapse, whichever comes first.  When the skill expires, either due to damage or time, the protective layer explodes off of you, dealing 155% weapon damage as Physical damage to enemies within a short (~5 yard) radius.

This idea is cool in concept- but again poor in execution.  If you’re surrounded by enough enemies that the 155% weapon damage to everything nearby is large, you’re probably going to die from massive blunt and sharp trauma very quickly.  If you’re not in a situation where that’s going to happen, then the damage is going to be dealt to few enough enemies that you don’t really care much.  There are some corner cases, mostly possible via Elective Mode, but generally speaking this isn’t really worth using.