Un extrait de Wowwiki qui donne une vision plus claire du tanking des 2 jormugars :
When Acidmaw and Dreadscale first appear, Dreadscale is mobile and can be moved around the room, however Acidmaw is rooted to the ground. Acidmaw can be tanked with a ranged class, but a melee class with high health is recommended. Acidmaw has an AOE paralytic toxin attack that can only be removed by a player that has Dreadscale's debuff called Burning Bite. He must be tanked facing away from the rest of the raid, and the raid should be spread out at least 10 yards from each other. He also does Slime Pool which is similar to Grobulus's green clouds. Every once in awhile he will inject a player with paralytic toxin, a stacking debuff that will slow you down to zero movement if not cured.
At one point during the encounter they will submerge under ground and become unattackable, they will reappear but in switched positions, Dreadscale will be anchored and Acidmaw will be mobile. Again they are best tanked away from the raid and kind of close together to alow players with the burning bile to cure the paralytic toxin. Once you kill one Jormungar, the other one will enrage so it's best to concentrate on Acidmaw, and casting DoTs on Dreadscale.