In 10 man, this is a very easy fight when you compare it with 25 man version or any of the heroic versions. there are simple things to avoid/do, do them right, and you will have no problems downing this boss from try one.
PS: if you are pugging this, the first 3-4 bosses will show you if you are having any nubcakes in your raid, get rid of them before this boss, or if you prefer carrying people then that's your problem :P
for this fight you need at least 1 ranged DPS, 2 tanks, 3 or 2 healers (i did it as 2 healers and got it just fine, although i was on my toes half of the time)
Phase one: 1- 1 ranged DPS to shoot permafrost orbs. 2- 1 tank for Nerubian Burrower, those adds have an expose armor debuff, the tank needs to make sure that he is tanking them on permafrost. Don't DPS the Nerubian Burrowers at this time, and wait till phase 2, since most of your dps will have nothing to do in that phase. Phase Two: Anub'arak will burrow approximately every 90 seconds, starting phase 2. He will pursue a random target with spikes throughout the phase and when he reaches them he will cast Impale. The spikes will gradually speed up until they hit the target, or hit a patch of permafrost. Standing on the permafrost (or being on the other side of permafrost from the spikes) will enable you to avoid the impale, but the permafrost will despawn. After a few seconds, he will select another target.
Swarm Scarabs will spawn rapidly, scarabs have little hp, seem to ignore most threat but stack the same stacking nature damage debuff on their targets, should be range kited and killed, or killed by melee not being chased by them. It is also possible to drag them across permafrost to gain more distance. After about one minute Anub'arak will surface and begin phase one again. He keeps threat from phase one.
Phase Three: It is advisable to kill off any adds currently active before pushing Anub'arak over 30%. He will not submerge or summon any more adds at this point. Anub'arak needs to die very quickly after hitting 30% as you will not last long under the effects of leeching swarm. It is not ideal to top off raid members as they will then be taking full damage from the leeching swarm, healing Anub'arak and prolonging the phase. Instead you will want to keep people at ~5,000 HP, so that they do not get gibbed by penetrating cold while also minimizing the amount Anub'arak heals.
Anub'arak does not have any other tricks and will die upon reaching 0% HP.