Dead Karthus body (not passive) can be ping targetted, but not other dead enemies [GAMEPLAY]

Description: Whenever Karthus dies and his passive disappears, the grey/black area where his body used to be can be ping targetted. I tried to ping other enemy's dead bodies, but it shows the regular ping. Ping target is like saying "focus your attention on ~~~~~~". Regular ping is like pinging a random spot on the map.

Reproduction: I guess kill a Karthus and ping target his dead body when his passive disappears.