Okay. Find the VC (virtual controller) for your instant deployment. Go all the way down to the section called "Device Events". Disconnect one AP from the cluster until you see the AP down trap in the Device Events for the VC. Copy the contents of that Trap to Notepad.
In the controller the AP down trap is like below (probably not like instant; just an example):
wlsxAPNumDown wlsxTrapAPMacAddress.0: 9C:1C:12:C1:05:94, wlsxTrapCount.0:2, wlsxTrapAPLocation.0: Kitchen-225, wlsxTrapAPIpAddress.0:192.168.1.186, wlsxTrapTime: 10/11/2016 14:12:34 UTC-5
So I copied the wlsxAPNumDown and created a trigger like this:
Now, when an AP goes down, this is what my alert looks like: