So, the nearly-extinct Slooms can be found in monster boxes, and sooner or later, one of them will drop a Zee Core to someone.

I would like to buy that core for 3k Crowns (the price is negotiable), because I aim to obtain a single copy of each material in SK. If you don't wish to sell it, I will pay 500 cr if you show it to me in trade.

It is probably one of the rarest materials in SK, although it's completely useless, so don't expect me to pay much higher (and probably they will reintroduce slooms even before it becomes useful, so it will be common by then).

IGN: Laucion