Sort of a complex one, yesterday we were playing a match on Summoner Rift. Our Cait laid down some traps in our jungle, and the enemy support came through with an active oracles to sweep out our wards and place new ones. After their support stepped on a cait trap, I was able to see enemy wards that were close enough to the revealed support.
Essentially, Blue cait trap revealed a purple zilean. Purple zileans oracles started allowing blue team to see the invisible purple wards, provided the purple wards were close enough to zilean.
I'll try and test this in a custom, as it might be a fluke and the wards were simply very freshly placed. I will bump with extra info when i have it.