Every bit as good as he once was despite the significant power creep in creatures
Prowess was certainly one of the favorite mechanics from Khans of Tarkir , and it shows up strong in TDM and remains a force in decks today
Better yet, these cards specify that a deck can have as many copies of Cid, Timeless Artificer as you'd like, so you can run a deck with every Cid in it
Then, Madam Mim can bounce him safely back into your hand, setting up a vicious cycle that, if it isn't stopped, can give you a huge lore lead
Kaya, Intangible Slayer is a wild seven mana, and youd hope youre set up enough to defend her from attacks by that point
Look, Firesong and Sunspeaker can do silly things, but there's a lot of crappy deck lists flooding the internet right now that worry me, like suddenly every card that people would unanimously agree are utter trash in Commander are suddenly amazing because it's moderately good when their 6 cmc commander with no built-in protection against removal is on the table