I know there’s been some people claiming that Languish is not that much of an upgrade from 4pc T9.  The following is a screenshot of a 10man Saurfang kill I did right after getting 4pc, and you can see that it clearly is an upgrade.

Let’s assume a 60% crit rate on Moonfire, which I think is actually a little on the high side, even given [Improved Moonfire].  Moonfire did 127973 damage.  If 60 percent of them crit and did double damage, 127973*1.60*1.03(meta gem) = 210899.504 damage.

Now, Languish did 108132 damage.  127973+108132=236105 damage.   That’s a 11% boost in damage over 2PC T9, and that’s giving Moonfire a very generous crit rate.  Giving a 55 percent crit rate, and 204308 damage, you’re looking at a 14% boost.

I don’t theorycraft often, so feel free to double check my math.

[Sunfyre's Nest RSS] | [Sunfyre's Nest on Twitter]

Note:  I’ve edited this post a bit since I’ve had time to sleep and actually think clearly, along with information given by commenters.

There’s been some questions on the forums regarding [Languish], and concerns over an apparent bug if you crit back to back within 2.0sec of each other, the Languish dot will never tick.  Languish will refresh, and the damage of Languish will roll, just like ignite, but you won’t be getting a rolling dot while you keep refreshing >2.0 seconds.  I’m not sure if this “feature” is the same for mages with Ignite, but I’m assuming the mechanic is the same.

[Sunfyre's Nest RSS] | [Sunfyre's Nest on Twitter]

Ghostcrawler confirmed that [Languish] is fixed in 3.3.2.  [source]

[Sunfyre's Nest RSS] | [Sunfyre's Nest on Twitter]

Patch 3.3.2 should be released Tuesday.  Included in it will be the final wing of Icecrown (but most likely not The Lich King himself).  In addition, [Earth And Moon] is going to be buffed to 2%/4%/6% self damage.  Hopefully they’ll add the [Languish] hotfix in as well.  For you PVPers, Season 8 will be released (And the final wing of Vault of Archavon.  Go get your free 264 tier pieces!)

[Sunfyre's Nest RSS] | [Sunfyre's Nest on Twitter]

Apparently [Languish] is currently set to a level 1 spell.  This is causing a 75% resist rate.  Ghostcrawler says they “can” hotfix it, but no news about when they will.

[Sunfyre's Nest RSS] | [Sunfyre's Nest on Twitter]