Yeah, as I mentioned earlier on this page [edit: er, last page], we've gotten a double chase at the beginning of each burrow every attempt for the past several weeks. Prior to that it never happened to us at any point in a burrow phase, so I've been assuming it was a weird bug with him not target switching properly, but since it doesn't really affect the strategy meaningfully, I haven't been horribly concerned about it. I'm certainly not disputing that it does happen, but based on the first couple months of TotC, it didn't seem like it's supposed to.

You do realize that the burrowers are Anub's adds, right? The smaller ones that leave the acid debuffs are called Swarm Scarab and nobody is suggesting any relation between those and Anub's impale target.

I'm not exactly what your remark is supposed to mean, but it's a fact that Anub *can* and *does* chase the same target twice in a row. The odds of this happening are, supposedly, about 1 in 24 or 1 in 25 depending whether or not your add tank(s) still have Expose Weakness on them.

Ok, I thought you meant the scarab debuff. We all agree that the add tanks can't be chased while tanking and the debuff is a likely way to implement this. I have seen add tanks chased the first time, so I'm not sure if the debuff faded or whether it's actually based on the targets of the burrowers, guess it doesn't matter much.
As for double chase, I find it odd that a nearly 8% chance didn't manifest itself once in our attempts. With 100 P2 (or 50 attempts that reach P3, which sounds reasonable) the odds drop to 1.5%.
I can see it being mitigated by boping and then PSing the next target, so it shouldn't be too big of a deal although even more reliant on random class CDs.
I'm also not sure why you're suggesting the raid should run TO the icepatch. In the 4-bop tactic, you want to be far from it.

A logical guess and probably easier for the code to query than whether a specific type of mob has aggro on a specific target.

So I'd go random choice, only limiter not targeting someone with Expose Weakness. Double chase has happened to us, I don't see why there would be a limitation to prevent it.

The only annoyance is that there still is a threat table involved. I suspect a great number of the "Random Shaman Switch" issues are from threat drops. Anub targets player X who is just using Feign/Fade/whatever. He immediately moves to a normal threat list - Resto aggro pulls. Begins to chase. That shaman's not casting, instead beating feet. Another shaman pulls threat via healing - random retarget.

This would explain every chase I've personally seen to date.

Except I'm elemental.
Also, he never swaps targets in the first place, our bossaddon would announce that instantly.

Correct - there is no problem with a double-chase. As he does not swap target there is nothing for the boss addon to detect - I believe it's tracking the application of the Pursued by Anub'arak. In a double chase it never changes, Pursued remains constant, nothing to trigger boss mod.

The threat explanation is only for when he swaps in the middle of pursuit. If your Hunters don't feign and Priests don't fade (they really should have no cause to do so) then ideally you've never seen a "random" swap.

Hello,

Regarding 25 hero Anub, i just checked some logs and can't figure why Leeching Swarm provides ~+30% more healing than damages, exemple :
kill : WoW Meters Online - Combatlog Replay
Add OT (player 'Finkill') healed Anub for 1.300.000hp via Leeching swarm : WoW Meters Online - Combatlog Replay
Add OT hit for 950.000hp from Anub because of Leeching swarm : WoW Meters Online - Combatlog Replay

This does not look particular as checking other players and other logs showed the same thing.

I expected either same figures or healing half of the damages (because of mortal strike, aimed shot, rogue poison, etc...)

Only reasonnable conclusion is it looks like the difference is because of mitigation dmg (passive skills, nature resistantce, etc...) does not affect healing.

I supposed that mean healing debuff does not work on 25 hero ?

Leeching Swarm doesn't heal for 1 point for each point of damage dealt. The "conversion factor" is different for different raid-sizes / modes. I don't recall the exact number right now, but for 25-heroic, the conversion factor is over 2 (maybe 2.3 or so), which is cut in half if a Mortal Strike debuff is up on the boss. The exact values for the conversion factor have been posted either in this thread or in a Druid tanking thread (I recall reading about them on EJ, but it's been a while and i don't know exactly where i found them).

Anub 25 heroic heals for 2.3 times the damage dealt (including absorbs, not including resists). MS does work and brings that down to 1.15. (Note: the multiplier used to be 2.6 but got changed in the week after Premonition's first Insanity.)

Example:

[21:52:46.908] Anub'arak Leeching Swarm Charsi 8718 (R: 2180)
[21:52:46.908] Anub'arak Leeching Swarm Deavan 7451 (A: 6494, R: 3486)
[21:52:47.578] Charsi Leeching Swarm Anub'arak +10026
[21:52:47.578] Deavan Leeching Swarm Anub'arak +16037

10026 is 1.15 times 8718, rounded up.
16037 is 1.15 times 7451 + 6494, rounded up.

These are the conversion factors:

The amount of life taken is multiplied by the above values and converted to healing on Anub. The healing is then reduced by 50% if MS is on Anub.

Here's part of the log report from our normal mode kill last week:

As you can see, Anub puts up the debuff, then starts leeching life from me. He heals for 77.5% (1.55 reduced by 50% from MS) of the amount of life taken. Interestingly, the amount healed is calculated after resists but before absorbs. Bubbling people has no direct effect on the amount of healing he receives, although it has an indirect one in that people can sit with lower HP without fear of dying, thereby healing him for less.