Don’t. Just Don’t. That’s the most arbitrary system i’ve ever seen in any game and it serves virtually no purpose. You already limited the amount of mobs we can have aggro’d to 5, and then you also feel the need to limit how many targets a certain AoE can hit? There’s nothing sillier than casting earthquake or taking 5 seconds to cast Meteor on a mob and see more than half of it either walk away unscathed and/or rape you.
Anyway, i think a system like this should be reserved to (if at all) splash damage attacks/skills. Those aren’t aoe for a reason, so it makes sense that they don’t oneshot an entire cluster. But a literal all spell you cast on the ground with a visible area? No.

