A dangerous cast stops, but the enemy keeps moving and attacking. That is not necessarily a failed ability. An interrupt can cancel a spell without applying the broader loss of control associated with a stun.
Games define these effects differently, so start with the current ability description and encounter rules. In some systems, a successful interrupt also prevents certain spells from being cast for a period. A stun may stop an action by disabling the target, yet behave differently against an immune boss or produce different combat-log entries.
Read the effect before assigning the job
Check whether the ability requires an active interruptible cast, its range, its cooldown and any additional effect. Then check the target. A spell that cannot be interrupted is not made interruptible because the group has more interrupt buttons available.
Version matters. Blizzard’s Midnight pre-expansion notes, for example, describe changes to interrupt durations and stun behaviour separately. That is a useful reminder to consult the rules for the version being played rather than borrowing an old duration from memory.
Make a simple cast-stop plan
For a fictional encounter, imagine a caster using a dangerous heal that can be interrupted and a separate movement ability that cannot. Assign the heal to one player, name a backup and agree what happens if the first player is out of range. Do not spend every available control effect on the first visible cast without understanding the next one.
After an attempt, review what happened in the game’s available log or replay. Did the ability land during the cast? Was the target immune? Did someone else stop it first? Distinguish a missed opportunity from a correctly timed action that the encounter rules did not allow to work.
A damage meter alone may not answer those questions. Nor does a low interrupt count automatically mean a player contributed nothing if the tool records other forms of control separately.
The practical gain is clearer coordination: know which action must stop, which effect can stop it and who is responsible. “Use crowd control” is too broad when the encounter needs a particular response.