Chilling touch does necrotic damage - it's Ray of Frost that slows the baddies. However, I used RoF extensively in my first and second attempts, and still got TPK'ed. The brains have a higher speed than the player character to begin with, and with the Dash spam one or both party members was at least "threatened" on every round. That left me with the "no-win" choice of disengaging, standing my ground, or risking an opportunity attack.
So I guess that means Pin Down wouldn't be an option either, if it functions similarly to RoF.
