This Weakaura will automatically mark mobs to be either Killed, CC, or Interrupted. Depends on the mob and encounter
*Must be leader of the raid for this to work*
To edit:
Under the Actions Tab click on the "Expand" button for the Custom On Init.
You will see a list of NPCIDs. Enter NPCID above if you want to include it to be marked, you can find NPCID on wowhead.
example:
https://www.wowhead.com/npc=128551/irontide-mastiff
Type this into the code.
["128551"] = true, --Irontide Mastiff
Credit for the coding goes to Causese