A cloud of light motes falls down on the scene at Vershab's incantation. This momentarily distracts the dark hounds, but their nature immediately reasserts itself: Much to the arcanist's dismay, the shadows soon take over, hungrily sucking in whatever light he produced.

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One of the mastiffs is blinded (it's S2, but it takes a DC15 perception check to notice it). Azkin and Lehasti made their saves.