The cold breath of the Water Dragon has the power to freeze even piping-hot magma.
The Ice Breath is the breath of the Water Dragon, capable of freezing even piping-hot lava. Serge was able to obtain some from the dragon; he required it to pass Mount Pyre to reach the Acacia Dragoons at Fort Dragonia. How he was able to carry something as airy as breath is unknown; perhaps it is Elemental in nature.
From: Key Items (Chrono Cross)