Duke wasn't worried that Robert would pocket the money. From what Duke had learned about Robert in this period, the man was just a wealthy player, unlikely to be tempted by such an amount.
If Robert really did embezzle these supplies while Duke was gone, it would mean there was no need to nurture this player further.
Upon returning this time, Duke definitely planned to make preparations regarding the Slave Mark, and would then decide whether it was necessary to take such measures.
After all, the human heart is unpredictable, and without the Slave Mark, one can never fully trust someone.
However, it's still uncertain whether the Slave Mark would be effective on players, and this must be tested to know for sure.
After packing up all the equipment in the makeshift laboratory, Duke took one last look out the window and then activated the Coordinates Earring, targeting the coordinates of the Wood Elf Plane.
