Lands of Algia 4E
This ceramic flask explodes in an icy haze when it hits, crippling its target with numbing cold.
Power (Consumable • Cold): Standard Action. Make an attack: Ranged 5/10; +9 vs. Reflex; on a hit, the target takes 1d10 cold damage and is slowed until the end of your next turn; on miss, the target takes half damage and is not slowed. Published in Adventurer’s Vault, page(s) 24
Found in the main chamber of the Temple of Nerilous