MapleStory Classic World damage formulas (CoT2 audit)

Why did I hit for that?

Damage is not one formula, it is a chain of them, and the gap between the percentage on a tooltip and the number over a monster’s head is where every argument about this game starts. Below is that chain run once, end to end, on a real skill against a real monster, with every intermediate value printed. The formulas page is the reference list; this is the working. The formulas come from the client audit made on Closed Online Test 2, which has not been redone for the Public Release, so until it is, these are the CoT2 formulas.

The chain, in order

1. The base rollYour stats and your weapon, multiplied by the skill’s percentage. This is a range, not a number: the low end and the high end differ by the mastery term and nothing else.

2. DefenceThe monster’s weapon defence divides it down. The curve is 100/(def+100), so the first hundred points of defence halve you and the second hundred take a third of what is left.

3. Element and levelAn element the monster resists halves; one it is weak to adds half again. The level penalty is the one that surprises people, and it is steep.

4. CriticalsNot a bigger hit, an expectation: rate times extra damage, folded into the average. The ceiling - every hit critting - is worked out separately.

Worked once, on a real row

Fighter, level 70 · Doombringer · against Tauromacis

Skill states

260%

the number on the tooltip

Base roll

1,916 – 2,176

before the monster is considered at all

After everything

1,548 – 1,758

what lands on this monster

If every hit crits

1,839 – 2,089

the ceiling, not the average

Step	Value	Where it comes from
Primary stat (STR)	292	Every AP point at level 70, less the weapon’s demands
Weapon attack	93	Doombringer, straight off the item row
Weapon multiplier	×2.5	Per weapon type and per action, from the client audit
Mastery multiplier	×0.88	Mastery 10/10. It lifts the minimum only, which is why mastery narrows your range rather than raising your ceiling
Defence factor	×0.800	Tauromacis has 25 weapon defence
Element factor	×1.00	A plain swing carries no element, so this is 1
Level penalty	×1.000	The monster is at or below your level, so there is no penalty
Critical expectation	×1.010	5% base rate at +20% damage, folded into the average
Average hit	1,653	The midpoint of the range, which is what a damage table should print

Every number in that table is produced by src/lib/calc/damage.ts on this request, not typed in. It is the same code path the planner decomposes with, so a figure here and a figure there cannot disagree.

The level penalty, which is the one that surprises people

Attacking above your level costs you damage on a curve, not a slope, and the first few levels are the expensive ones. This is the whole argument for the level windows on the training tables: a map full of monsters five levels above you is not a slightly slower map.

Levels above you	Damage multiplier	You lose
at or below	×1.000	0.0%	No penalty at all
+1	×0.995	0.5%	Quadratic: each level costs more than the last
+2	×0.980	2.0%	Quadratic: each level costs more than the last
+3	×0.957	4.3%	Quadratic: each level costs more than the last
+4	×0.926	7.4%	Quadratic: each level costs more than the last
+5	×0.889	11.1%	Quadratic: each level costs more than the last
+6	×0.847	15.3%	Quadratic: each level costs more than the last
+8	×0.758	24.2%	Quadratic: each level costs more than the last
+10	×0.667	33.3%	Linear from ten upward, and already down by a third
+15	×0.571	42.9%	Linear from ten upward, and already down by a third

The rest of it

Accuracy and the hit test, avoidability, the heal formula, damage over time, the mastery table and the element states are all on the formulas page, each marked with how confident the project is in it. Every second-job attack run through this chain at a stated level 70 is on the damage rankings, and your own character’s version of it is in the planner.