Things that we want to see in Limited or casual Constructed but usually not in multiples for complexity reasons tend to go into uncommon
Youd need to play then banish three Pawpsicles on turns 1 and 2 (youre allowed to target any character and it doesnt need to be damaged) and have Belle Inventive Engineer played on turn 3
Flash creatures either function as one-for-one removal spells (Hired Blade), as two-for-one removal spells (Sentinels of Glen Elendra is better at surviving combat than Ashcoat Bear), and as flexible curve-fillers (Cloaked Siren lets you hold up interaction and have a threat if you dont need to use it)
Upon reaching the third chapter, the Saga transforms into an Enchantment creature, with Kiki-Jiki having the ability to copy nonlegendary creatures
Aaaand finally, the matchups (I realize that Ive probably lost good portion of my readers 500 words ago)
I hope my rambling gave you some insight into how milling is designed