This deck is a relatively simple, somewhat budget approach to Skull Servants in Master Duel that only uses a few high rarity cards aside from the meta staples that you should already have. The deck largely runs itself; Clown Zombie mills Baking from deck, Baking grabs Prince & Mare, dumps Prince. Prince mills a Servant and Lady, then banishes those for a King, and Mare discards for a Lady. Pretty basic, but what makes it shine is how versatile the deck can be with the extra deck. Since you have so many low attack monsters, Geonator Transverser can practically steal games by giving the opponent a weakling. Borrelsword can easily be link-climbed into from the basic opener by using Uni-zombie to go into Halqifibrax. And with some very careful planning, you can go from Halq into Shooting Riser into Ametrix and shut down opponent's attacks.
Of note is Nibiru. While in most decks, Nibiru requires you to have removal to avoid a massive token, KoSS can often simply overpower the token, especially with the help of Wightprincess.
Of the UR's present, i would say that the 3 Un-zombies and one Avendread Savior are non-negotiable. They make it so easy to get what you need, and their ability to discard both from the deck and hand can come in clutch. Many of the others are Staple cards that can be subbed in and out as your budget provides. Thankfully, a majority of the power players here are all found in the same Secret Pack, so 3-4 10pulls will give you most of what you need.
As for improvements to the deck, I would look towards MBT's excellent list that utilizes That Grass Looks Greener, found here:
https://www.youtube.com/watch?v=PxUO3oLaGcw .
Thanks for checking my list out!