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Interrupts in Mythic+: Kicks, Stuns and the Casts That Must Be Stopped

Interrupts are the second place time hides in a key, after the route. They are also the place where the log is easiest to misread. This guide is what we learned building the interrupt accounting in Keystone Delta, with the traps that cost real hours and a friend's correction to fix.

The flag the game uses

No nameplate addon keeps a list of dangerous casts. Plater, Platynator, the Details cast bar and Blizzard's own casting bar all ask the client one question, C_Spell.IsSpellImportant(spellID), added in patch 12.0 for "a spell that is lethal if not interrupted", and paint the bar red from its answer. The flag lives only in the client. It is not in the spell data tables you can download, and Warcraft Logs does not expose it. We dump it in game after each patch and ship it as the red must stop tag on every interrupt row. The full list per dungeon, with the mob that casts each spell, is the must-stop casts page.

Must-stop is not must-kick

The flag marks casts that must be answered, not casts that must be kicked. On Altar of Fangs, Evolve is crowd-control only (Evolved is no cast at all, it is the buff the mob gains when Evolve runs its course), and The Writhing Coil's channel breaks when you run out of it. A first version of our tool said "a kick was ready" for every flagged cast that landed; a Guardian Druid who read his own report caught it. Now a cast is treated as kickable only when Archon's interruptible list for the dungeon names it, or when either log shows a real kick stopping it. Fourteen of the forty-six flagged casts on our worked example were of the other kind, and they are labelled "not a kick: move or crowd control" and kept out of the kick budget.

What Warcraft Logs records, and where its table goes blind

The Interrupts table on Warcraft Logs is built from interrupt events. It is blind in two ways that matter in Mythic+.

Crowd control that cuts a cast bar is logged as an interrupt event without the spell that did it. Capacitor Totem, Incapacitating Roar, Blinding Light, Hammer of Justice, Blind and Typhoon all did this in our logs, fifteen times in one run, and the table filed them under no spell. Rebuilding from events fixes it: take every enemy cast start, give it a window to that caster's next action, and match the interrupt events on that caster instance inside the window. Envenom went from 33 to 40 recorded stops on the same log.

Crowd control that breaks a channel leaves no interrupt event at all. Warcraft Logs synthesises the event for a broken cast bar, and a channel has none. The only trace is the debuff landing on the caster mid-channel. The millisecond timeline proved it: Evolve starts at 690.87, the Roar lands on that Evolutionist at 692.89, the mob melees and starts a new cast the moment the Roar drops. So the tool also reads crowd-control debuffs applied to enemies, and an aura landing on a caster mid-cast counts as a stop credited to the aura's source. That took one player's count of stops from 6 to 15.

Channels and hardcasts count differently

A hardcast emits a begin event and, if it finishes, a cast event. A channel emits one cast event at its start, and nothing when it ends. Counting channel cast events as "landed" called Evolve "10 of 12 landed" when ten of those ended at three seconds of a six-second channel and only two ran long enough to matter. Full length is the longest gap to the caster's next action; anything under 90% of that is "cut short", shown with a scissors mark. A channel cut short by something the log does not name stays "cut short"; the tool never attributes it to a player without an event.

Two things still invisible

A stun that lands between casts prevents the next one and leaves nothing to count. And when two players stop the same cast, only the first is credited. Both are limits of the data, not of the reading.

The kick budget

Per run, the group's kicks plus stops a minute, against the must-stop casts it needs to answer. When the tool suggests chaining two packs, it compresses the must-stop starts of the two split pulls into the merged pull's seconds and checks whether the kick supply covers them; the suggestion carries the result as a tag. Chaining is only advice if the interrupts can carry it. A third tag, mechanics, says whether anything in the merged pull stacks with the mob count: an ability that fires on death or damage no button stops is choreography, not healing.

Reading the table

Per enemy spell: began, stopped (kicks and control separately, with who and with what), landed, cut short. "Began" does not equal "stopped plus landed": a cast also ends when the caster or its target dies. Sort is must-stop first. Rows appear only when the cast was stopped at least once or is flagged; otherwise every uninterruptible cast in the dungeon would read "nobody stopped it".

A flagged spell with no cast bar is never a row. The game flags the buff a mob gains when its channel runs its course (Evolved, from Evolve) and plain auras (Tempest Stormshield, Deep Corruption) alongside the casts themselves, and in the log they look exactly like a channel start. Cast time and channel flags are read from the client tables, and anything with neither is shown as what the cast gained, never as a cast that "landed".

Frequently asked questions

Where does the must-stop flag come from?

From the WoW client itself: C_Spell.IsSpellImportant, the function nameplate addons call to colour a cast bar red. It is not available in downloadable spell data or in the Warcraft Logs API, so it is dumped in game after each patch.

Why does Warcraft Logs show fewer interrupts than Keystone Delta?

The Warcraft Logs table files a cast bar broken by a stun or knock under no spell, and a channel broken by crowd control produces no interrupt event at all. Keystone Delta rebuilds the count from cast starts, interrupt events and crowd-control debuffs on the caster.

Is every must-stop cast a kick?

No. Some flagged casts are answered by moving out of them or by crowd control. Keystone Delta only counts a cast against the kick budget when Archon or Method lists it as interruptible, or a real kick stopped it in either log.