Moved out of thread to stay on-topic:
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there is a lot of ways to realise that.. Actually around 1 year ago i made a working system of a dynamical change of a vision range.
it's a item ability if i remember correctly, that can be used for change vision.
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Interesting. Yeah, I figure there's a way to do it with coding/triggering... I'm not all that good at it, though, so what / meant was a version that almost entirely uses Object Editor work-arounds.
If going for a "as close to AoM Atlantean Oracle as possible"... Well, I have no way of detecting 'non'-movement (without checking every unit over & over again). But perhaps a Channeling Summon (Tornado, etc), where the dummy summon provides a big ring of vision. Then I can have it die (-HP regen) and give it a "summon on death" ability which creates a "lvl2" dummy summon with *greater* vision.
Do that a few more times (total of 3, or 4 rings) and I'm set!... Except after the 1st one dies, the unit will stop Channeling. Dang.
Well... Maybe the first one is the "spawner", and makes the 2nd one, which is the original "1st" (i.e. dies to make the next, which dies to make the next). Hmm....