We're playing Commander on a program called Magic Online
(A copy of a permanent spell becomes a token.) If you don't cast the copy (perhaps because there are no legal targets available or you don't want to), the copy will cease to exist
Ravensburger also made sure that all the promos were not only highly playable staples but that they all had beautiful art to get both players and collectors competing for them
If it actually flips, Red Decks might be in trouble, but Cecil's existence likely strengthens their position in the metagame, if anything
Put her as the leader of a casting-cost matters build that uses effects like Explosive Revelation to smash people with higher casting costs or effects like Rush of Knowledge with an expensive card such as Draco
With this many cards, most games will not even see half of the planar deck, which makes them less repetitive since there are always more lands to explore