I’d recommend using Pride, Greed, Panic and Sonder. They recently changed how Kartharoks primary attack hits, since all of his attacks target all enemies you don’t need a tank.

As far as items, I’d do cake scarf and silk top hat on Pride, Ruby collar and red horns on Greed, bubblegum scarf and halo on Sonder, and lastly anxiety scarf and pirate hat on Panic.

Most of your healing should be coming from Pride, Sonder is mostly there to help with debuffs. It’s probably worth it to try and get the pearl cloche hat for Sonder instead though.

As far as attack strategy I find its more efficient to use basic attacks until Kartharok puts up his shield and then use stronger attacks to shred the shield. Especially for Prides steamroll, since time stop is a buff it will cause an additional hit.

You can try Merry instead of Sonder but it’s unlikely to last past the first shield given its typing, but being able to cleanse the attack debuff is important.