Invisible templates for GMs

So I know you guys are doing things with templates, but I had another thought (scary I know). It would be nice if GMs could place template that couldn't be seen by the players.

Take the Death Tyrant (5e version). "Negative Energy Cone. The death tyrant's central eye emits an
invisible, magical 150-foot cone of negative energy." The main effect is anything in the cone can't regain hit points. While the players wouldn't be able to see where the cone is, the GM need to see the cone so he can negate healing spells and such. So this would be a case where the ability to place a template that only the GM could see would come in handy.

A second scenario I can think of is difficult terrain. One of your Feature Library examples has been using templates to apply the effects of difficult terrain. An invisible (to the players) template would allow the artwork on the map to be seen, while still allowing d20pro to handle the effects of the difficult terrain.