Nightmare
The firsf step of every dungeon run was to destroy the skeletons that were at the start.
As with the previous difficulty increase he assumed he would be fighting more skeletons than before, or at least more difficult skeletons.
What he wasn't prepared for was an arrow striking him in the shoulder before he could even use his mana sense to find the skeleton.
It dealt over half of his health in one shot so he had to attack back before he was slain since there was no cover in this cave.
When he saw the skeleton deep in the dark depths of the tunnel he cast a trio of nova needles to destroy it.
With the help of his two unique items he could feel how easy controlling shadowfire mana was, it was a derivative of shadow mana after all.
The Voidbeast fang also seemed to make his projectiles sharper.
He wasn't sure how it all worked yet as he had been to excited to try out the next difficulty of the dungeon.