The Skeletal Marauders in Necrotic Wake have an important ability named Boneshatter Shield. IDs per my logs:

Cast: https://www.wowhead.com/spell=343470/boneshatter-shield
Buff: https://www.wowhead.com/spell=344423/boneshatter-shield

When it gets cast, you want to pump damage (or even a CD) into the Marauder to break the shield while it's up (8 seconds), so that you get free damage off of it.

Ideally LittleWigs would notify the player on cast start, I think. Perhaps it's even possible to have a timer (here's my transcriptor logs: Transcriptor.zip), but I think just having a notification on the cast would get us 80% there.

When it gets cast, you want to pump damage (or even a CD) into the Marauder to break the shield while it's up (8 seconds), so that you get free damage off of it.

Just to add, breaking the shield seems to oneshot the Marauder, on +17 at least (412k average damage per hit in my logs).