How can I detect when a player upgrades and then revert it back to 0 and perform an action like drink a potion? This is an idea in Dungeon Escape. I want to know how to do that.

Mineral or gas loss detection then preforms the actions.

This will work in conjunction with giving the upgraded building (Terran Engineering Bay/Protoss Forge/ect...) to another player during the upgrading action and then giving it back to its respective player. This will prevent the upgrade from completing, as well as setting the time for the upgrade to complete to a ridiculous amount, so no matter what, it won't upgrade.

But how do you revert the upgrade back? On that map you press s with the forge selected and then it drinks a potion and your shields stay 0.

Edit: Nevermind, thanks bronto .

These actions. Giving the player who owns the upgrade building to another player and then giving it back to the original player, will prevent the upgrade from completing. You should also set the time that the upgrade is set for, to a ridiculous time, so that it won't upgrade no matter what.