While we're satisfied with the way the rune system works overall, we're making a few major changes to the mechanics that will ultimately help death knight players feel less constrained. Here's the rationale behind the changes, followed by an explanation of how the new system will work.
* In the current rune system, any time a rune is sitting idle, death knights are losing out on potential damage output. By comparison, rogues spend most of their time at low energy levels, and if they're unable to use their skills for a few seconds, that energy builds up and can be spent later, minimizing the net loss from the interruption.
* A death knight's runes, on the other hand, cannot be used until they are fully active. If a death knight ever goes more than a few seconds without spending an available rune, that resource is essentially wasted. Because the death knight is pushing buttons constantly, it can be difficult to add new mechanics to the class because the player doesn't have any free global cooldowns to use them. We can't grant extra resources or reduced cost, because there is no time to spend them. Missing an attack is devastating, and it's impossible to save resources for when they're most useful.
* Additionally, each individual death knight ability has a fairly low impact on its own, making it feel like most of the death knight's attacks are weak. The death knight's rotations are also more easily affected by latency or a player's timing being just a little off. At times, it feels like death knights aren't able to take advantage of their unique resource mechanic, which can diminish the fun.
* The new rune system will change how runes regenerate, from filling simultaneously to filling sequentially. For example, if you use two Blood runes, then the first rune will fill up before the second one starts to fill up. Essentially, you have three sets of runes filling every 10 seconds instead of six individual runes filling every 10 seconds. (Haste will cause runes to fill faster.) Another way to think of this is having three runes that go up to 200% each (allowing extra "storage"), rather than six runes that go up to 100% each.
* As this is a major change to the death knight's mechanics, it will of course require us to retune many of the class's current abilities. For example, each ability needs to hit harder or otherwise be more meaningful since the death knight is getting fewer resources per unit of time. Some abilities will need to have their costs reduced as a result.