This was a sweet throwback to a classic card called Plague Rats, which got bigger and bigger the more Plague Rats you had on the battlefield
People playing Standard, with all the new set releases and new fancy cards, and a big rotation every 2-3 years (see whats currently in Standard here)
Ancestral Katana Banishing Slash Bushi Tenderfoot Bushi Tenderfoot Call to Glory Eiganjo Uprising Experimental Synthesizer Godo, Bandit Warlord Godo, Bandit Warlord Imperial Blademaster Imperial Oath Mothers Yamazaki (playtest) Naomi, Pillar of Order Oathkeeper, Takeno's Daisho Samurai's Katana The Eternal Wanderer The Wandering Emperor
Every fast mana card printed since then has been measured against it
If the game was starting to get stale for you this past month, let me be the first to tell you that Lorcana is extremely back, baby