It's frustrating when you don't actually see the unit killed, but it is not in the same place and it didn't move much.  I kept on Counterspelling the Dark Wizard's Despair, until a time came when he had two turns in a row!  When I came back six or seven turns later, he was nowhere to be seen and there were not powerful AI units there that visibly were damaged by the Despair!  I would love it if another player kills a monster unleased on the world by a random event, that you get a suitably boastful message from whichever side did it, and which random event monster they killed.  Then you know and you get closure, rather than frantically casting Ineluctable Vision or exploring all over the map Just In Case.

It would be even better if this facility was available to modders too, for the custom event monsters they create.