Purge

Contract

Aprg is CAbilityPurge (parent AAsm). Apg2 is a TFT melee alias whose code is Aprg, so it shares CAbilityPurge and reads its own row through abilityitem_t.code. Item AIlp (CAbilityLightningPurge, parent Aprg) is registered on the same procedure. Creep ACpu also has code=Aprg but remains unregistered here. Orb/totem AIpg / AIps are out of scope.

Rawcode	Archive	Notes
Aprg	ROC and TFT	classic Purge (no pause)
Apg2	TFT only	Shaman melee Purge; adds unit/hero pause
AIlp	ROC and TFT	Item Purge / Lightning Purge
ACpu	ROC and TFT	creep Purge — unregistered

Casting strips every timed status from the target and deals DataC damage when target->owner is set (summoned). The movement slow/pause is applied only to hostile targets. A friendly cast still performs its dispel without adding Bprg or stopping movement. Retail JASS verification of stock TFT Apg2 confirmed the distinction: at 1.5 seconds the friendly target moved 382.881 units versus 403.491 for its unpurged control; the hostile target moved 80.865 versus 385.253. This does not establish behavior for the other aliases.

Authored fields

WorldEdit AbilityMetaData labels (WESTRING_AEVAL_PRG*):

Field	Stock Aprg	Stock Apg2	Meta name	Runtime
DataA	5	5	Movement Update Frequency	initial slow; see below
DataB	0	0	Attack Update Frequency	unused
DataC	400	400	Summoned Unit Damage	S_SpellDamage when owner set
DataD	0	3	Unit Pause Duration	non-hero immobilize window (seconds)
DataE	0	1	Hero Pause Duration	hero immobilize window (seconds)
DataF	—	—	Mana Loss	unused
Dur / HeroDur	15 / 5	15 / 5	—	slow buff lifetime (Bprg)
BuffID	empty (ROC) / Bprg (TFT)	Bprg	—	empty falls back to Bprg

Apg2 ubertip: enemy units are immobilized for <DataD> seconds, then slowed by a factor of <DataA> while recovering over <Dur>. Immobilization is a move lock (reject order_move, 100% S_PurgeMoveReduction), not a separate stun buff. Do not treat stock DataA=5 as “zero speed”; pause comes from DataD/DataE.

DataA slow + gradual recovery

Ubertip “factor of DataA” means stock DataA=5 starts at speed 1/5. Fixtures often author a remaining-speed complement in (0,1] (e.g. 0.5); those use 1 - DataA as the initial reduction. DataA <= 0 is a full stop.

After any pause window, reduction lerps from that initial value down to 0 over the remaining buff lifetime (Dur - pause). At the instant pause ends, reduction is still the full initial slow; later samples are weaker.

Data Flow

AbilityData.slk (Aprg / Apg2 / AIlp)
  -> DataA/C/D/E, Dur/HeroDur, BuffID, targs, Cost, Rng
CAbilityPurge
  -> clear timed statuses (skip S_StatusIsUndispellable; Cyclone DataA==0)
  -> hostile target only: unit_addtimedstatus(BuffID or Bprg); store spell->code in status.data
  -> friendly target: dispel only; no Purge movement status
  -> S_SpellDamage(DataC) when target->owner
S_PurgeMoveReduction / S_PurgeIsImmobilized
  -> read DataA/D/E from status.data (casting rawcode), not hardcoded Aprg
  -> after pause: initial slow * (1 - elapsed_after_pause / slow_window)
s_move order_move / ai_move_walk
  -> S_PurgeIsImmobilized rejects/stops translation (same family as Bens/BEer)

Purge ubertip says “Removes all buffs”, but Cyclone authors Can Be Dispelled (DataA). ROC DataA=0 cyclone survives Purge's clear loop; TFT non-zero does not. Unit-target selection of an already-cycloned unit is still blocked by S_SpellAllowsTarget; see Cyclone.

Diagnostic Workflow

build/bin/ability_audit -data 'data/Warcraft III' -raw Aprg
build/bin/ability_audit -data 'data/Warcraft III' -raw Apg2
build/bin/ability_audit -data 'data/Warcraft III' -raw AIlp

Verification

make test-wc3-engine WC3_PATTERN='wc3_spell.purge*'

Focused tests cover alias procedure sharing, Aprg authored DataA slow, Apg2 DataD immobilize + expiry restore, Hero DataE pause, summoned DataC damage, gradual post-pause recovery, and friendly dispel without movement status. t_spell.c also verifies hostile slow and summon damage with explicit player-relation setup.