Reverberation. A third-level talent in the elemental tree that reduces the cooldown of your shock spells from six seconds to five. Most shamans agree it’s a weak talent and best avoided unless you plan to PvP. So why did a pure PvE shaman such as myself bother maxing it out? Why not Elemental Focus and Eye of the Storm?
To start with the last question, that’s simple. My spell crit chance is only 9%, which I think is not enough to merit the point in Elemental Focus. Eye of the Storm seems only useful for casting lightning bolts at melee range, and even then only after being the victim of a critical strike. Maybe as an all-out elemental shaman I’d be more into the lightning bolt slinging business, but as it stands this talent is just too specific to be useful for me.
So, what makes Reverberation such a good choice then? Very simple: interruption. That’s admittedly not something I do a lot when healing a group, but it’s a necessity when I’m solo and fighting caster enemies. (I’m Scryers, so I have to fight blood elf warlocks all the time.)
The shaman tool of the trade for interruption is Earth Shock. To understand just how awesome Earth Shock is, you must first understand what it does:
- Firstly, it’s an instant cast nature spell that deals damage. Quite a lot of it too, if you’re using the max rank (which is what I tend to do when I’m solo’ing)
- Secondly, it interrupts spellcasts. I strongly recommend enabling enemy casting bars in your interface menu, so you see exactly when to interrupt.
- Thirdly, it locks out the school of magic of the spell that the enemy was casting before you interrupted it. This lockout lasts for two seconds.
Now let’s assume that the average caster enemy’s offensive spell has three seconds casting time. Let’s also assume that most enemies are one-trick ponies; they have one offensive spell and they will attempt to cast that spell over and over. I don’t have any solid evidence for these two assumptions, but from experience I can say that they generally ring true.
How do these numbers add up in practice? After you interrupt an enemy spell, it will prevent him from casting the same spell for two seconds. After those two seconds, it will probably immediately start casting it again. This spell would have hit you three seconds later… if it wasn’t for the Reverberation talent, that reduced your Earth Shock cooldown from six to five seconds.
In theory, you could continue to simply keep interrupting every five seconds, but in practice you’d probably want to alternate every two shocks with one Grounding Totem. This still enables you to intercept the enemy spell, but now you also have some extra time to cast a shield on yourself, or drop a Searing Totem, or whatever best suits your fighting style. The bottom line is that Reverberation makes it entirely possible for a shaman to fight caster enemies without ever getting hit by their spells.
A word of warning for applying the above routine in a PvP setting: most players are smarter than letting their spells repeatedly get interrupted or grounded. Although your mileage may vary 
