Blood Queen Lana’thel is a straightforward fight. You have three debuffs to watch out for, two of which you’ve probably seen before.
The first debuff is called Essence of the Blood Queen, AKA the vampire bite. It usually goes to the second player in her threat table but I’ve seen it go to someone else so don’t quote me on that. The queen will bite someone in the raid and give him or her this debuff. Assuming it goes to you, you will have sixty seconds of pure DPS bliss: damage is increased by 100% and cause no threat for 60 seconds. Of course, it’s still a debuff, so here’s the catch: once that minute is over, you will receive Frenzied Bloodthirst. Your action bar will be replaced by a single button. Find another DPSer, target him or her, then hit the button. This will make you bite that person, dropping Frenzied Bloodthirst and bringing back Essence of the Blood Queen. Your bite target will also have Essence. You and your victims will eventually pass this to the rest of the raid. If you don’t bite someone, you’ll get MCed.
The second debuff is Pact of the Darkfallen. This one draws a red line that connects certain members of the raid, causing damage during its duration. Close the gap to get rid of it. The final debuff is Swarming Shadows. It’s like Jaraxxus’ fire debuff except it’s purple. You can use Cloak of Shadows to remove it even before it drops a trail. Otherwise, you’ll leave a trail of fire while it’s on you so run but try to keep your movement as tight as possible so you don’t end up making a mess in the room.
At some point during the fight she’ll go up in the air. You’ll get feared while she AOEs the raid. There’s little that you can do at this point except to hit Cloak of Shadows and hope you time it right. Once she lands, it’s back to her old cycle, minus the bite.
The gimmick of the fight, DPS-wise anyway, is managing the bite. If it doesn’t go to DPS, or to DPS ASAP, she’ll still be alive by the time everyone gets bitten.