Theyre actually viable in gameplay
A creature cant have a negative power or toughness, but the negative modifier will still count against other effects that modify power and/pr toughness
Though it's impossible to say why sales like these occur, as there are a variety of factors that could contribute, it's clear that they don't always make sense
I like Boreas Charger and Vesperlark providing some recovery from mass removal if Sephara has been neutralized
Even minimal strategic insights, or little strategy, can influence the outcome of a game, making it accessible to newcomers and casual players
with the numbers exceeding the base sets number of cards, theyre sometimes known as Secret Rare cards, which is a common name for cards of this type in TCGs