I'm thinking something similar and I think it's a good idea.
Making Two small regions at the entrance and exit of the region. One to activate "WoodCombat Trigger" and another to Disable "WoodCombat Trigger".
When the unit enters "WoodCombat Activate" that trigger turns on, creating creeps around the hero, without having to create the whole region. And when the unit enters "WoodCombat Deactivate" creeps just stop spawning... I'll try and report
EDIT: What happens if I create multiple Events "Unit Enters Region" in the same trigger?
I removed all the region, and placed two regions on each entrance/exit, one to add the unit to "Wood_Group" and another to remove it.... The thing is that, since units spawn at 800 AoE of the hero position, creeps can spawn outside the woods, down the mountains, or over the mountains (in the top-left corner of the img), etc...
I'm thinking about a really poor quality solution: Create a region that covers good part of the woods, from the center, and spawn units in a random point of that region and order these to attack the Hero, wherever he is... At least works for this wood...
Red Region is a "Safe Zone" I'd just use "Unit enters Region - Unit belongs to Neutral Hostile - Unit - Remove unit"
I like the idea, but... it's too much work, don't you think?... xD I think it's a lot simpler, and almost equally efficient to spawn in that region inside the wood. I'll may try that system you're suggesting in another region...
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