Effects & keywords
Burning: 3 magic damage per stack, every 1 second (flat, does not scale with attack power; stacks up to 50). Example: 10 stacks = 30 magic damage/second before resistance. Duration is set by the applying skill. It never misses, is never guarded or critical and goes past Barrier, but the target's Magic Resistance still cuts it (x 100 / (100 + resistance)). On a Wet or Heavily Wet target each tick is x0.8.
How the math works
Burning stacks landing on this unit x (1 + 100%). Burning damage taken by this unit x (1 - 40%).
When it runs: Two hooks: before each effect application, and while each hit's numbers are set up.
What it applies to: Only Burning whose target is the Fireproof holder. Burning you put on enemies is not changed.
Things the tooltip does not tell you
- With Become Fire, the self Burning grows, but the Become Fire Magic Attack stacks do not; Fireproof only looks at Burning.
- The damage cut applies only to hits whose source is the Burning effect.
Read out of the game binary of build 25846389. Refactor.Combat.SkillRelated.SKILL_FireProof.Passive_FireProof$$OnEnable@0x942234, Refactor.Combat.SkillRelated.SKILL_FireProof.Passive_FireProof$$AddBurningStackRoutine@0x942534, Refactor.Combat.SkillRelated.SKILL_FireProof.Passive_FireProof$$IgnoreBurningDamageRoutine@0x942614
Numbers
| Range | 1 |
| Start delay | 0.2s |
| End delay | 0.2s |
| Cooldown | 0s |
| Energy cost | 0 |
| Skill points to learn | 6 |
| Required level | 4 |
| Basic attack skill | no |
| Delay scales with attack speed | yes |
| Can target over walls | no |
| Raw values | 100, 40 |
Prerequisites
Requires: 
Ignition
Tree position
Burst Skill Tree - Tier 2, column 1