Neptune

Neptune is a Summon sequence of the Mercury element. When three Djinn of the Mercury Element are on standby, the Neptune Summon sequence can be activated. It resembles a titanic purple whale with red eyes and beige tusks surface from an ocean and launch a Mercury beam attack with its frontal snout. The enemy party is assaulted with downpours of water resembling waterfalls.

Neptune has a base Mercury power of 120 and also does additional damage equivalent to 9% of the enemy’s maximum HP. Neptune is the first truly useful Mercury summon sequence. It is twice as powerful as Nereid but uses only 1.5 times the amount of Djinn on standby. However, there is no boss fight in Golden Sun where it can be used effectively, particularly because the Boreas summon sequence can be attained shortly after Neptune can.