Damage & Healing

This page documents how damage and healing get encoded, and the formulas that produce numbers matching the de-facto community standard. All field positions assume advanced combat logging is enabled.

SPELL_DAMAGE Suffix

SPELL_DAMAGE, SPELL_PERIODIC_DAMAGE, RANGE_DAMAGE (and their _SUPPORT variants) all use this suffix at fields 31+. Total field count: 42. The advanced block (12–30) describes the target for these events.

SWING_DAMAGE Suffix

No spell prefix, so offsets shift -3. Total field count: 38 (or 39 if off-hand). The advanced block (9–27) describes the source for SWING_DAMAGE and the target for SWING_DAMAGE_LANDED — they're the same swing logged twice.

Critical: SWING_DAMAGE_LANDED is not a separate hit. It's the same auto-attack reported again with the target's advanced block instead of the source's. Counting both SWING_DAMAGE and SWING_DAMAGE_LANDED doubles every melee swing.

ENVIRONMENTAL_DAMAGE Suffix

The advanced block comes first in this event, then the environmental type, then the damage suffix. The source GUID is always 0000000000000000 (no actor — the world did it):

When a player dies from a knockback or platform fall, this is the event that records it. Death analysis pipelines that only look at SPELL_DAMAGE / SWING_DAMAGE will silently miss those deaths.

Empirical note: This layout was verified against real M+ and raid logs. Total field count is 39. The environmentalType string lives at field 28 — after the advanced block, not before it.

SPELL_HEAL Suffix

SPELL_HEAL and SPELL_PERIODIC_HEAL:

SPELL_ABSORBED — The Three-Way Event

SPELL_ABSORBED records "an attack happened, but a shield ate it." It encodes three or four entities: attacker, defender, absorber (the shield-caster, sometimes the same as the defender), and the shield spell. It comes in two formats depending on whether the absorber is the same as the defender:

Format 1: 22 fields — shield on someone else

Format 2: 19 fields — self-shielded

Your parser has to count the fields to figure out which format it is. There is no header to disambiguate.

The Damage Formula

effectiveDamage = max(0, baseAmount + blocked + resisted - max(0, overkill))

• Overkill IS subtracted. Effective damage delivered, not raw damage rolled. One-shot a 1M HP boss for 5M = 1M counted, not 5M.
• overkill = -1 means "didn't kill." Treat negative as zero before subtracting.
• Don't add the absorbed field. It's informational; the absorbed damage already lives in a separate SPELL_ABSORBED event with its own amount. Adding both double-counts partial absorbs.
• Add blocked and resisted. They were dealt; the target just mitigated them.

The Healing Formula

effectiveHealing = max(0, amount - overheal)

• Don't subtract absorbedToShield. That portion was real healing converted into a shield buff; it counts.
• Some "absorbs" are not healing. Cheat-death and Stagger-style mechanics get logged as SPELL_ABSORBED but should NOT be added to healing totals:

Pet Damage Attribution

Pet damage gets credited to the owner. Three signals, ranked by reliability:

You will see pet damage before you see the SPELL_SUMMON. Pets summoned before combat (warlock demons, hunter pets, DK ghouls) start dealing damage immediately, and ownership data arrives later. The right architecture: buffer unknown-owner pet damage and retroactively reassign when the owner is discovered. Get this wrong and warlocks parse 30% lower than they should.