Mobs casting an AoE should aggro mobs the AoE hits.

[Jimjam]

Regarding Fire Drakes,

Feb 23 2000 at 6:16 PM

Their fire effect, though it doesn't do that much damage, relatively, is an area effect, so any mobs near you when fighting a drake will join and kill the drake, and take the kill. So, if you pull drakes, pull them away from lava crawlers, and other stuff.

https://everquest.allakhazam.com/db/npc.html?id=1976#m2356

[derpcake2]

This was disabled so people couldn't set up faction wars.

In classic you could charm a caster, spam /pet attack from a distance onto another mob from another faction, and when your pet started to cast, you could break charm before it finished casting, which would end up with the mobs fighting each other, after which you could train more mobs from both factions into the fight, which could be exploited for massive gains.

This lasted until luclin on live when devs got annoyed at people single-handedly clearing out Shadow Haven, although the arena in PoTactics was already known for this being exploited on a massive scale.

So no, this won't be coming back.