Research from the Estate Scrolls
Since you took a long rest you were able to glean the following from the scrolls as you become more familiar. The translation is still rough, and reads like staccato thought mashed into the parchment.
“The Stygian Magician tasked the Stygian Fencer, Stygian Lancer, and Stygian Knave saying to them, “Enter the realm and with our gifts, trample the lion. Trample the asp and the wyrm. Stygian Strider and Stygian Archer shall recover the destruction, and we will free Stygian Berserker to march under the water.”