Chakram Retriever itself can definitely set up some fun synergies and combos by untapping creatures, but theres far better ways to do that without paying 5 mana
Battle Of Hoover Dam Reviving the Tarkir Siege concept with a fresh Fallout finish, Battle of Hoover Dam is one of the most underplayed MTG cards in Aristocrats brews
Likewise, a deck like Death's Shadow Aggro that is extremely land-light can get away with playing fewer lands in part because it has 12 cards that cycle for free
That said, if you want to play Sultai Midrange, I'm not even sure that buying the Golgari Midrange Challenger Deck is worth it since you're still going to need $400 of cards to end up with the optimal build of the deck
Honorable Mention: Yuriko, the Tigers Shadow While neither a rat nor directly synergistic with rats, Yuriko, the Tiger's Shadow does have commander ninjutsu, and theyre both one of the best Dimir commanders, and one of the best aggro commanders