So cool! You made a time dragon, and I made a crazy herald of a time dragon! We had some similar ideas between our submissions, especially your “The End” and my “Your new home, the onyx realm”, A DPS check! I love it.
I think my favorite feature is as sand through an hourglass, the flavor is fun, and the mechanic is interesting.
My only feedback, both BREATH OF FORGOTTEN CENTURIES and HURL THROUGH INFINITY have 5e saving throws, and target multiple players. In my opinion, that will slow down an already lengthy combat with lots of abilities to keep track of. I would recommend doing the single power roll with potencies to keep turns from dragging. Just my opinion.