Notar is part of the Stone Lord's crew and can be found in his hideout. If the party solves the Sluice Gate puzzle or opens the gate with an Athletics check, Notar and the rest of the crew will be hostile and attack the party once they reach the end of the tunnel.
Throw a shard of ice that deals 1d10Piercing damage. It explodes and deals 2d6Cold damage to anyone nearby. It leaves an Ice surface. On miss, the shard of ice still explodes.