MS getting changed?

Ghostcrawler on healing debuffs:

I agree it's an issue and we do have some plans.

However, we're going to back off of talking about Cataclysm for a little bit. We're excited about it, so we've been wanting to share our philosophy, plans and ideas as they relate to class design. However, it may be a little too soon. I think it's clear that some players are mistaking our excitement for Cataclysm as our giving up on Lich King. ("Cataclysm will fix it.") That's not our intent nor plan, but I can understand how you might draw that conclusion. We'll talk more about the upcoming expansion soon (tm).

I'm sure I'm not the only player who thinks that 50% mortal strike is just too hard to balance. I've taken to playing a healer class again recently (holy paladin this time), and the difference between mortal and no mortal strike is just mind blowing. As long as mortal strikes exist in their current form, you would need absolutely mind blowing burst (alot of the popular wizard cleave variations) or a very very high amount of CC in order to get anywhere without one of the three classes that have a 50% MS on your team. For comparison, although the frost mage and shadow priests 20% MS is somewhat noticeable, it's not a night and day difference when it comes to attempting to outheal damage like a 50% MS is... more of a nice but not overpowering advantage in terms of sustained pressure.

So how do you balance mortal strike? There are a few different possibilities that people (including myself) have suggested. The first and most obvious one is simply to nerf all mortal strike effects. 30% seems like a much more reasonable number, large enough to notice but not bringing the same black-and-white qualities of current MS. Would you buff or nerf the current caster MS effects? Maybe even remove? I'm not sure.

Another possibility is just to give everyone an MS effect of some sort, or just make it so widespread that almost any team is going to have it. This has the advantage of freeing up arena team compositions alot, but blizzard has already stated they want to cut healing and damage relative to health pools. If they implemented this change, they would probably have to buff healing appropriately to be able to keep people up through MS a bit better, which is something I don't think they will (or should) do.

One possibility that I believe was first suggested by Affix was making caster mortal strike and melee mortal strike both 25%, and making them stack. I'm actually not a big fan of this - for a start, it does feel like "artificial" game balancing - using a single debuff to force teams into certain compositions instead of how the classes work together in general (like how rmp works for example, classes that amplify each others strengths and cover each others weaknesses). On top of that, it restricts the amount of viable comps even further than the current mortal strike system. I understand alot of people feel stacking melee or stacking casters can be cheesy, to an extent I agree. However, it's important to remember alot of people feel that say, RMP is cheesy as well... whatever beats you often gets described as so. Also, personally I don't have a problem with the idea of stacking two wizards so much as the way it's played right now - spamming damage on whoever is in line of sight most of the game instead of focusing on scoring interrupts + CCs.

Lower the uptime of mortal strikes. This is probably my favorite solution - maybe even leave them at 50% (or nerf them a little, who knows), but make it so that they're not up all the time. Rather, you apply them when you need to burst, much like you might apply a CC to a healer. There would probably have to be a bit more to applying them than just hitting an instant ability too - maybe it could have a very high energy/rage/focus cost. Something that makes you make sure you want to do it before you actually hit it, or penalizes you for using it at a bad time.