[Spell] Aoe damage and spells, do they utilize region searches for detection?

[Shalaator]

Let's say I command my Archmage to use Blizzard on a location.


How does the game detect which units to damage?

Does the game call ALL units on the map and then individually check to see if each unit is in that small circular region for each damage period?


I must know how this works since I have several ideas utilizing aoe effects that would actually trigger insane lag if this was true.

 

[Uncle]

It searches in a radius around the target point. Pick every unit within 300 range of target point of ability being cast. I imagine the game would run like complete crap if it worked the other way.