Several years ago I won a tourney and received a code; today I decided to finally use that code and chose Mark of Time. Naturally I upgraded it, threw it into my favorite Time deck, and took it for a spin against AI3. My understanding was that Mark cards were not valid targets for removal, but when I played mine it was put into the permanents right next to my towers and pendulums, and was blown up by removal the very next turn. Is this supposed to happen; was my understanding of Mark cards incorrect?