If we first look at Standard, we can see there are plenty of spells players want to cast that cost five or more, especially Leyline Binding (which never really costs five), and the enchantment side of Virtue of Persistence
Join the fray with powerful bending masters, hybrid animals, and lovable allies wielding blades, boomerangs, and the occasional cabbage
I especially recommend the cycle of common cards from The Lord of the Rings: Tales of Middle-earth , as they all make for great fixing options in Commander, Pauper, and even more powerful formats like Modern and Legacy on occasion
The mana value might keep it out of many decks, but Firesong and Sunspeaker has great value for Boros burn decks
It happened because we decided to not do cantrips in the Urza's Saga block
12 Current Finest, 1999 Pokmon 1st Edition set, says the two cards that have been difficult for him to track down in PSA 10 have been Wartotle (#42) and Lass (#75), which is a Trainer card