Quote Originally Posted by joretapo View Post
Imagine I copy Glacial Chasm at end of turn. During upkeep, I let the original Chasm die and Thespian Chasm gets one cumulative upkeep. At the end of opponent's next turn, I copy Thespian Chasm. Does the cumulative upkeep get reset or not?

Thespian chasm is effectively a new copy of Glacial Chasm.
You copy Thespian Chasm with what? Or are you say Thespian Chasm copies something else? Your wording isn't clear, but the Thespian Chasm will still have an age counter on it from the first Glacial Chasm upkeep trigger, so there's no way to reset cumulative upkeep by copying something else in the interim. If you have two Thespian's Stages, then copying the Thespian Chasm with the second Stage will be fine since the latter does not yet have any age counters on it.

Also, what's with the recent influx of people who can't be bothered to type well?