So if you play a creature, and your opponent casts a spell that kills it, but you counter that spell, but your opponent counters that counter, the Stack helps you figure out what exactly happened amidst the chaos of all that spell-slinging
Unlike the flashback mechanic to cast spells from graveyards, such as with Past in Flames or Dralnu, Lich Lord, the way Kess casts spells is not itself an alternative cost, so you can pay alternative costs for your spells with her (Cyclonic Rift)
Wilds of Eldraine limited has been a lot of fun, and I look forward to exploring it some more in the weeks ahead
Formats are just faster than they once were, and these slow, painful cards become especially punishing when you're facing down faster, more aggressive cards from your opponent