Sanguinarian

TL;DR: Pull the whole room after Rattlegore & bomb them.

Some quick facts you want to know.

The NPCs for the achievement are only found in the Butcher's Sanctum after the room Rattlegore is in.
There are 16 Krastinovian Carvers (further only called Carvers) in the room, each with 1 stack of Boiling Bloodthirst. After a Carver dies all of his Boiling Bloodthirst stacks can jump to other Carvers if they are close enough. At 99 stacks of Boiling Bloodthirst their attack speed is increased by 495% and damage taken increased by 990%. Having 99 stacks is the maximum stacks they can get, you cant get more than 99.

First lets see what we can work with:
As mentioned before, there are 16 Carvers in the room, but you only need 10. Which means you can safely kill or ignore 6 Carvers before trying to complete the achievement.
When you enter the room you can see 4 Carvers in your range along with a Flesh Horror. You want to kill all 4 of them so you can get to the other Carvers in the room. On the left side you have 1 Carver standing alone, 1 patrolling the front side of the room and 2 Carvers standing together with a Flesh Horror. There is one more group of 2 Carvers standing in the back of the room on the left side but we wont be using them. On the right side you have 1 Carver standing alone, 2 standing together, 1 patrolling the back and the middle of the room, 1 standing still in the middle of the room and 1 standing in the back with a Flesh Horror.

Now how to do the achievement:
I have made a guide to give you a general idea of how (I think) it can be done in the most effective way.
1) You start by pulling 3 Carvers, each starting with 1 stack. CC one and kill one of the two you have free. Make sure the one you kill is close enough to the CCed one so when it dies the one CCed also gets stacks.
2) Now you have two Carvers with 2 stacks each. CC one of them and then pull another Carver with 1 stack. Kill one of the two Carvers with 2 stacks, again, making sure the two other Carvers get the killed Carvers stacks.
3) Now you have two Carvers, one with 4 and the other with 3 stacks. You want to CC the Carver with 3 stacks so your tank doesnt get too much damage. Pull a new Carver with 1 stack and kill the Carver with 4 stacks.
4) Now you have two Carvers, one with 7 stacks and the other with 5. CC the one with 5 stacks, pull a new one and kill the Carver with 7 stacks.
5) By now you should get the idea of how this works. Whenever you kill a Carver you CC the one with less stacks than the other, pull a new one and always kill the Carver with the highest number of stacks.

Here is a simple chart to see how it works (the crossed over number means you are supposed to kill the Carver with this number of stacks on him):

1. 
   
2. 1 1 1
3. 
   
4. 2 2 +1
   
5. 
   
6. 4 3 +1
   
7. 
   
8. 7 5 +1
   
9. 
   
10. 12 8 +1
    
11. 
    
12. 20 13 +1
    
13. 
    
14. 33 21 +1
    
15. 
    
16. 54 34 +1
    
17. 
    
18. 88 55
    
19. 
    
20. 99
21. 
    

This is all just how it would work if you had the Carvers coming to you one by one but thats not the case. I would say you want to pull the double Carver groups first while tank damage is still managable. It is up to your group setup to decide how you want to pull them and what CCs you use. This is only to explain how the achievement should be done.

As a lvl 100 MM hunter with a 717 iLvl, this is very easy. Aggro the whole room and then single target each Krastinovian Carver and kill them one by one. After each kill, the remaining Carvers' boiling bloodthirst buff will double (2, then 4, then 8, then 16, etc.) until the last one reaches 99 stacks. Once you see a Carver with 99 stacks, AOE the remainder of mobs. I got my ach on the first try. EZ PZ Lemon Squeezy... GL Guys :)