I have certainly used it in many a format with cards like Carrion Feeder and Patriarchs Bidding to win on the spot
Phyresis Outbreak gives poison and might kill opponents creatures Feed the Swarm enchantment removal in black Vat Emergence gets a creature back and proliferates Spread the Sickness destroys a creatures and proliferates Pact of the Serpent strong tribal card draw Living Death swap graveyards with battlefields, great after sacrificing your whole board to draw cards Skullclamp sack small rats for card draw Thrumming Stone if you go the Relentless Rats or Rat Colony route Coat of Arms your rats will be huge Bolas's Citadel this card is dumb lol, lots of casting power and then you hit Gray Merchant of Asphodel and keep going lol Icon of Ancestry kinda draw buffs rats...is ok Contagion Engine proliferate twice each time you activate Eldrazi Monument gives creatures flying indestructible and +1/+1 Grafted Exoskeleton gives a creature infect, great with Crypt Rats Sword of Truth and Justice proliferate sword Bad Moon buff all black creatures, opponents too Phyresis gives infect again good with Crypt Rats Greed card draw Vraska, Betrayal's Sting proliferate planes walker I know that's a lot but hopefully gave you some ideas to work with
In other words, Achilles will come down for its reduced cost often, provide a decent threat, and buff your entire board as long as he remains on the battlefield
Leyline of the Guildpact from Murders at Karlov Manor really blew it wide open, making the Scion trivially easy to cast
Atogatog Copy And Paste Atog is a popular creature (maybe less loved if you played Pauper) that spun off into a series of other Atog cards, each with the gimmick of sacrificing a permanent to give temporary stat boosts
