Necromantic corruption not only makes minions take conditions from their master, but also one another when they should only take conditions from the minion master himself. This is easy to reproduce by having anyone apply a single long condition to the Minion Master himself, and watching it bounce between minions. Using a condition with a very noticeable particle effect (such as chill or burning) helps too.
I noticed this when the enemy team captured tranquility while I was standing on the point. This is very easy to reproduce in this same manner and is very easy to see as the minions who are under the chill effect turn a blue color.