QUOTE(DooM77)
In one map I've disabled doodat state for Zerg Beacon and it became partially transparent and word "Disabled" appeared under its name but in other map I did the same thing and beacon became unselectable. How can I choose effect I want to reach?
If you own the beacon, have vision for whoever owns the beacon, or have a detector near the beacon, it will be translucent, just like when you detect any other cloaked unit. (Dark Templar, Observers, etc.)
If you can't detect the beacon, and you've never detected the beacon, it will still look normal, but will be unclickable.
If you've detected it at some point, but don't detect it anymore, the beacon will cloak, and all you'll see is the blue glowing part.
Tutorial on invisible beacons:
here.
QUOTE(DooM77)
I saw medics blinding player's units at the beginning of chrono legion and blinded heroes at the beginning of Death Knights. How to reach this effect? Is there a special AI script for this?
Medics will automatically blind enemy units that have 81 HP or more. (if the optical flare ability is enabled, and the medic has enough energy)
List of ways to get the computer to use abilities:
here.