More importantly, a healer must be able to keep up with the damage from more than one DPSer for a short period of time. Consider 5-person Arena matches. Commonly, teams are built of four DPSers and one healer. (We're not looking for comp arguments here, just the basics.) For at least a few seconds, a healer should be able to keep a focus target alive. The same goes for three-person Arena teams. See where this is going? Healers, by nature, need to be able to withstand a huge amount of DPS for a short time.
These balance issues come into sharp focus when you're one lone PvP damage dealer trying to whoop up on a healer. What was once a fundamental basic of balance philosophy becomes a huge pain in the neck. Here's how to handle the situation.
Interrupt reliably, and interrupt well. If you're a DPS character, you probably have an interrupt, and you should know how to use it. If you're not already in the habit of interrupting spellcasts, get practicing now. Find some reflex tests, make sure your interrupt button is in a convenient place, and practice until perfect.
Before getting into interrupts more deeply, let me say this: Left between the choice of interrupting any heal and interrupting nothing, interrupt any spell that is about to go off. That being said, a few strategies can make sure you get the most out of your interrupts.
First, most interrupts have a brief lockout period. In a lot of ways, this helps make sure latency doesn't rob you of an effective tactic. For our purposes, though, that lockout gives you a window of opportunity. If you save up your own cooldowns and potions for one huge burst of damage, then you're walking around with a huge, potential wallop all at once. Save that wallop for after an interrupt.
The window of opportunity isn't huge. But it gives you a head start in this cat-and-mouse game. A few seconds can spell a big difference. Whenever you've executed a successful interrupt, immediately unleash hell.
The second chance is to wait for a healer to be distracted. Most healers run with team members. When you see the healer's partner is on the rope and requiring a heal, interrupt the healer immediately. This spreads out the healer's resources; do they heal themselves or their buddy? Either way, you're using up the healer's resources.
Don't make any long-range plans. Killing a healer is a lot of work; it's a long, dirty business. But there's hope. Healers are balanced around mana availability. If you methodically apply damage over time, you can hope to run down his mana pool. The notion here is that you might eventually string together enough crits and procs that you overwhelm his mana pool. It is possible and it does happen, if you're patient.
This is not a fast process, though. I've had to chase healers around for 15 minutes before I eventually burned through cooldowns and defenses. If you're truly determined to kill that healer, pop open a beer, kick back, and settle in for a long one.
Get help. This is the thing nobody wants to hear. If you're trying to kill a healer, you're best off getting help. The same tactics apply when you're talking about two DPS characters versus one healer; hopefully, the time will just be vastly decreased. The likelihood of the healer making a mistake will increase, and the two of you will more quickly be able to capitalize on that error.
Plan ahead. If you expect to get in a fight with a healer, you have a counterintuitive measure you can take. You have a stat that does you no good against a healer: resilience. Resilience protects you against damage, which isn't really the strong point of a healer. (Exceptions exist, of course, as more than a few healers are capable of decent PvP DPS.) Still, if you have the option of swapping out some of your resilience in favor of raw damage, that will help you overwhelm the healer's mana pool more quickly.
Of course, if anyone else comes by during the long, drawn-out fight, you'll get squished without your own resilience on hand.
If you have any other tips to share, leave them in the comments below. If we all band together, then perhaps we can kill a healer.
Visit the WoW Rookie Guide for links to everything you need to get started as a new player, from how to control your character and camera angles when you're just starting out, to learning how to tank, getting up to speed for heroics and even how to win Tol Barad.