Tank death chance: tuning and granularity


Mr. Robot seems to hate my iLevel 425 - 435 tanks. Even with the simulation set to the default damage setting (which I think should correspond roughly to LFR), they have frequent deaths (100% death chance) despite typically negating 88-89% of incoming damage.

For starters, I am wondering if this is right - I would have thought an iLevel 430-ish tank would have a non-negligible chance of surviving an encounter of LFR or Mythic 2 difficulty.

I tweaked a few things that could be considered flaws in my build (azerite traits, low-tier essences) but it had virtually no visible effect.

It seems the explanation must be some combination of:

The encounter damage is too high
The healing is too low
My health (which means basically item level) is too low

I have read what I think is the most recent explanation of how the TUF stat works:

Whether the 100% death chance is WAI or not, it makes the simulation metric very difficult to use, since it’s almost half the metric, and since changes in damage negated are pretty small.

In the process of trying to understand what is going on, I realized you have some interesting information buried/hidden in the simulation report, specifically the average number of deaths per encounter, which is listed as “Overkill” in the report.

This is much more granular than just a binary “you died or didn’t die”. For high survival probability, it is essentially the same as what you do now (if you have 0.1 deaths per encounter, the fraction of encounters you survive should be very close to 90%).

But if you have a 100% death chance, the present metric does not distinguish between dying (say) twice per encounter and dying five times per encounter.

A more granular metric could treat death as a Poisson-distributed random variable, whose mean is the average number of deaths per encounter (i.e. “Overkill”). Then the effective death chance, in percent, would be:

100*(1 - Exp[-(mean number of deaths per encounter)])

The script is tuned around heroic raiding damage levels. If you don’t have gear appropriate to that level, you’re not going to make it :wink:

You can use the NPC Damage Multiplier to apply a negative multiplier to get the damage down closer to normal mode raiding levels. Have you tried that? 430ish gear is really low level gear at this point - even a small amount of mythic dungeons could get you up above 450 very quickly.


Thanks - I understood that with no damage mod the tuning was for LFR/Mythic 2 (and the dropdown actually says Mythic 2). If it’s heroic, that makes a lot more sense.

I found with (IIRC) -32% NPC damage I would get around 50% survival.

You might still want to consider the more granular death metric, although admittedly it isn’t relevant for highly geared characters.