How about giving her a choice of permanent consumable item that gives her boot stats? She can benefit from only one just like boots. She's really missing out on boot stats especially since she benefits alot from Mpen, Tenacity, and swiftness.
She doesn't benefit much from MPen or Tenacity.
MPen is an early game snowball stat, which Cass does not do. Later on in the game it's only really useful against squishies, but Cass is usually attacking tanks because she doesn't have the tools to try and attack the squishies first. This was still her best choice for boots in previous patches.
If she gets hit by hard cc she's done, reducing the length of a stun by 30% is not enough for Cass to survive the encounter.
Swifties did provide a niche use to help her deal with slows, but it was still a rare niche compared to Sorc's boots which were still just mediocre on her.
Champions buy boots for the movespeed, the other stats are a nice little cherry on top. Without having to buy boots for the movespeed it frees up gold to spend on better and more efficient combat stats.
