Diablo III- Skills Article XLVI: The Demon Hunter, Hunting Skills- Preparation

Preparation (Cooldown 45 Seconds): Restore all Discipline.

Your Discipline pool, as a Demon Hunter, is tiny by default- roughly half the size of a Barbarian’s maximum Fury pool.  This makes it very easy to empty out, even with the lowest-cost skills that draw from it.  Having the ability to restore it fully every so often gives you a good opportunity to draw on those skills all over again.  The difficulty in this is that Discipline takes the place of one of the three skill options you can take that spends Discipline.  So, unless you’re really heavily leaning on your Defensive and Devices skills, this isn’t going to wind up worthwhile most of the time.  Sure, everyone’s going to want it every so often, but with Vault, Companion, and Marked for Death occupying the same slot, most Demon Hunters are going to find themselves either not using it most of the time when they have it, or not using it anymore.  Fortunately, the runes you can apply will make this skill more usable- but there’s a limit to how much they can change.

Invigoration (Cooldown 45 Seconds): Restore all Discipline, and increase your Discipline pool by 10 for the next 5 seconds.

Invigoration increases the impact of using Preparation, which isn’t a bad thing to be able to do.  Sadly, five seconds isn’t really long enough to take advantage of the increased pool for more than the one refill you get out of Invigoration, but it’s still a good third again as much Discipline as you usually have.  If you don’t mind waiting most of a minute between shots of Preparation, and always have a use for more Discipline above all else, then go ahead and take this rune.

Punishment (25 Discipline): Restore all Hatred.

Punishment, on the other hand, makes Discipline hugely more usable.  Combined with Shadow Power, this can give you a huge barrage of damage to dish out every so often.  By removing the cooldown, it lets you operate the skill more often- but since it requires most of your Discipline pool, it’s not as big an improvement in speed as you might like.  Still, it essentially becomes an entirely different skill when you apply this rune- so you should always give Punishement its own separate chance from your other uses of Preparation.

Battle Scars (Cooldown 45 Seconds): Restore all Discipline and 60% of your Health

Given that a number of the skills that use your Discipline are defensive skills, chances are that if you run out of Discipline and enemies are still around, you will be taking some damage.  Applying this rune to Preparation makes it an excellent ‘panic’ button for restoring your ability to use evasive skills and simultaneously protecting you against any damage taken while you use them- or after you empty your Discipline out again.

Focused Mind (Cooldown 45 Seconds): Restore 45 Discipline over the next 15 seconds.

Focused Mind essentially improves your Discipline efficiency over a period of time, rather than refilling the pool.  Since the resource is gained as time passes, you can use it with only a small dent in your Discipline, and then spend away over the next brief while with assurance that you’re going to continue regaining Discipline.  Additionally, it restores more Discipline than the base skill, so if you find yourself with occasional periods of ‘Discipline hunger’, you can use this rune to alleviate that.

Backup Plan (Cooldown 45 Seconds): Restore all Discipline.  There is a 30% chance the cooldown will not be triggered.

Backup Plan is a little weird- if you want to rely on having your Discipline refilled more frequently, it’s not going to do that.  It will, however, give you an occasional shot at restoring your Discipline again shortly after you fire it off.  You should really only use this if you are able to check on Backup Plan immediately after using it despite likely being busy in mid-battle.  Simply put, it’s not something you can rely on- but it’s an occasional boost that you’ll enjoy when it occurs.