## The HP of solo mobs in Khitai

## Measuring mob HP

Lately I’ve been somewhat obsessed by the idea of measuring the amount of hit points (HP) that various mobs have. In principle this is very easy: you kill the mob and analyze the combat log, summing up the amount of damage done to it and subtracting any healing that the mob may have received. In practice it turns out that these results are annoyingly imprecise; if you repeat this several times with the same mob, you’ll get a slightly different amount of HP each time.

Partly this is because your last attack, the one that kills the mob, may have exceeded the amount of HP the mob had left at the time; e.g. if the mob was down to its last 100 HP and you hit it for 300 HP, 300 is what will get written in the combat log and you’ll end up overestimating its HP by 200. To minimize this problem, I was playing my necro and finishing off each mob with a few whacks of my talismans; such melee attacks are extremely feeble since a necro doesn’t have much strength and combat rating.

Despite this precaution, there is still more variance in the results than I’d like; I’m not sure what other source of error there is. Perhaps the game deliberately selects a mob’s HP at random, from a certain (rather narrow) range, when spawning that mob.

## A model for the HP of Khitai solo mobs

I was going around the Khitai level 80+ playfields, killing various kinds of mobs and writing down their HP. Gradually a very interesting pattern emerged.

You find that, on each level, the amounts of HP that mobs have tend to cluster around a relatively small number of possible values. Furthermore, the relationships between these values are the same on any level. For example, at any given level (from 80 to 85) you will find that most humanoid mobs have the same amount of HP; then there are some weaker mobs that have only 85% as much HP; bosses have 275% as much HP; and so on.

And finally, if you compare the results across levels, you will find that the amount of HP increases in a systematic manner, by 7.5% per level (relative to the HP of a level 80 mob).

So you can divide the mobs into several ‘types’ and you will find that the HP of a mob is then fully determined by its type and level; to compute it, you just have to take a certain base HP (a constant), multiply it by a fixed coefficient that depends only on the type, and then multiply it by another fixed coefficient that depends only on the level.

*mob_HP* = *baseline_HP* × *type_coefficient* × *level_coefficient*

As I mentioned above, the level coefficients are very simple: you simply increase the mob’s HP by 7.5% of its level-80 HP for each level above 80. Thus, for a level 80 mob the coefficient is 1, for 81 it’s 1.075, for 82 it’s 1.15, for 83 it’s 1.225, for 84 it’s 1.3 and for 85 it’s 1.375.

## Mob types

The type coefficients will of course depend on which type you take as the baseline. The following lists shows the types along with their coefficients; I used the ‘normal’ type from the list below as the baseline as it seems to be the most common, and choosing it as the baseline also leads to the most elegant results (a 7.5% increment emerges again, as we’ll see).

- Feeble (0.775): this type mostly contains animals, e.g. wolves and firebirds.
- Weak (0.85): this type also mostly contains animals, e.g. snakes.
- Normal (1.00): this is the most common type; in particular, nearly all the humanoid mobs fall into it.
- Tough (1.70): twice as much HP as the ‘weak’ type; this type mostly includes big animals such as kappas and water buffalo.
- Boss (2.75): as the name says, this type consists of boss mobs.

Note that the 7.5% increment appears here as well, just as it did for the level coefficients: feeble = normal − 3 × 7.5%, weak = normal − 2 × 7.5%, tough = 2 × weak.

There are a few other types that appear more rarely:

- Double normal (2.00): horse archers in the Northern Grasslands.
- Double tough (3.40): wild stallions in the Northern Grasslands.
- Tough boss (3.57): 30% more HP than a regular boss; Scarred Ursa in the Northern Grasslands.
- Double boss (5.50): Reanimated Mammoth in the Northern Grasslands.
- Triple boss (8.25): Senior Warmonk in the Northern Grasslands.

The Senior Warmonk, in the southwestern part of Northern Grasslands, appears as either a level 80 or a level 81 version (it’s random). The level 81 version, with approximately 58400 HP, has the highest amount of HP I’ve seen on a solo mob in a solo playfield so far.

A few other anomalies I’ve noticed:

- Baio the Guardian in Chosain is marked as a boss but has 30% less HP than a regular boss would. This almost puts him into the ‘double normal’ type.
- Level 80 Wild Horses in NG have a type coefficient of 0.70 (i.e. another 7.5% step below the ‘feeble’ type); on the other hand, level 81 Wild Horses fit nicely into the ‘feeble’ type.
- Level 82 Peasant Workers in Chosain have an anomalous type coefficient of 0.75.

## Estimating the baseline HP

So far we’ve seen the coefficients that will appear in our formula for mob HP from the beginning of this post; but what about the baseline HP?

We’ve seen that this is nothing else than the HP of a level 80 normal-type mob. After killing numerous such mobs, the lowest estimate of their HP that I could find was 6587 HP.

Another approach is to take the HP of some other kind of mob and divide it by the coefficients (now that we’ve established them). For example, we can estimate the HP of the level 81 Senior Warmonk (I got 58440), divide it by 1.075 (its level coefficient) and by 8.25 (its type coefficient), and we get 6589 HP. These things seem to fit together pretty nicely, so I’ll stick to 6587 as my estimate of the baseline HP.

## Finally, a table

Now we can plug this baseline HP into the above formula and obtain estimated amounts of HP for each combination of type and level. It turns out that the results match my empirical measurements (obtained by analyzing logs after killing various kinds of mobs) very nicely. If you move your mouse over a number, you should see examples of mobs with that amount of HP in the tooltip.

Type | Type coef. | Level and level coefficient | |||||
---|---|---|---|---|---|---|---|

80 1.000 |
81 1.075 |
82 1.150 |
83 1.225 |
84 1.300 |
85 1.375 |
||

Feeble | 0.775 | 5105 | 5488 | 5831 | 6254 | 6636 | 7019 |

Weak | 0.850 | 5599 | 6019 | 6439* | 6859 | 7279 | 7699 |

Normal | 1.000 | 6587 | 7081 | 7575 | 8069 | 8563 | 9057 |

Tough | 1.750 | 11198 | 12038 | 12878* | 13717 | 14557 | 15397 |

Boss | 2.750 | 18114 | 19473 | 20831 | 22190 | 23549 | 24907 |

* The asterisk marks combinations of type and level for which I didn’t find any mobs. This occurs at level 82 because there are relatively few mobs at that level in Khitai: Northern Grasslands is mostly 80–81, Chosain and Kara Korum are mostly 83–84.

## Comparison with old-world mobs

I haven’t yet explored the HP of old-world (i.e. pre-expansion) mobs thoroughly enough, but from what I’ve seen so far, there aren’t as many different types there; only the normal and boss types are present. The bosses have 2.75 times as much HP as normal mobs, same as in Khitai. The HP increases by 20% (of the level 80 value) for each level above 80 (as opposed to 7.5% in the case of Khitai mobs). The baseline HP is much lower than in Khitai.

Level | Pre-expansion | Khitai | ||
---|---|---|---|---|

Normal | Boss | Normal | Boss | |

80 | 4610 | 12668 | 6587 | 18114 |

81 | 5526 | 15199 | 7081 | 19473 |

82 | 6647 | 17742 | 7575 | 20831 |

The Breach and Forgotten City follow the old-world pattern as well, although some of the bosses there have an extra 50% HP (which pushes them to 19000 HP at level 80).

Very interesting 🙂