So I was thinking about tenacity pets over the weekend, and wondering if the crocolisk could possibly top the gorilla as an aoe tank. This got me to wondering exactly how much threat the “moderate amount of additional threat” on thunderstomp is.
Well, I spent way too much time searching around online and couldn’t find an answer, so I decided to run some tests myself. I’ll write this up later in a more comprehensive article, but for now, here’s what I did:

I took out Burke (level 80) and found me some high level mobs. With Recount on to measure damage, I put pet on passive and told him to thunderstomp and nothing else. Then I removed my melee weapons and proceeded to punch the mob until I drew aggro.
I know that in melee I need 10% more threat than the aggro target to pull aggro. So once I pulled aggro I FD’d and looked at the numbers (letting the mob wail on Burke). I knew how much damage thunderstomp did, and how much damage I did, and that I did 10% more than Burke’s threat.
I repeated this a lot. I did it waiting for multiple thunderstomps. I was punching to as to cause as little damage per hit as possible, so that when I pulled aggro I wasn’t too far over (like I would be meleeing with big damage hits).
Finally I looked at my data. I found that the threat wasn’t consistent — and not just that most of my numbers would be a bit high ’cause I did more damage than needed, but they were way off. Most interestingly I noticed that the additional threat component was WAY high when thunderstomp critted, suggesting that it was somehow based on damage.
To test that, I got naked.
I removed all of my gear (leaving shirt and tabard for the sake of modesty) to lower Burke’s spelldamage (which is based off my AP) and tried again. Sure enough, Burke did a lot less damage on thunderstomp, and the threat component was also lower.
So after hashing the numbers again, I found one perfectly consistent point: the threat component was always 150% of the damage that thunderstomp did. So every point of damage thunderstomp does causes an additional 1.5 threat. We can increase the damage, and the threat, by increasing our RAP, thereby increasing the pet’s spelldamage. From what I could tell, it looked like the spelldamage just added directly onto the thunderstomp damage.
Also, it seems that pets gain 12.85% of hunter AP as spelldamage. This percentage stayed in place from 2400 AP through 3600 AP. However, down below 2400 the percentage changed to 12.81, suggesting that it’s tiered somehow. Anyone know what the exact formula is, or if there’s another tier at higher RAPs?

For example, can a level 12 hunter tame a level 34 pet with help from a level 80 hunter via freezing trap? If so what level would the 34 pet become?
no it can’t. hunter can tame only pet of equal or lower level.