Water Ninja

Water Ninjas are level 55 monsters located in the Port Anchorage dungeon. They have 100,000 HP, 5,000 MP, 880 Defense and they do approximately 1,000 Damage (according to the Spy ability). Even though these monsters have MP they do not seem to cast any spells, thus making them melee attackers only. Water Ninjas are very farmable since they have a chance of dropping Water Cores, which are used in unlocking the Aquamancer class. Water Ninjas can drop the following items:

Water Core at a 0.1% drop rate

Zaigon Katana at a 0.1% drop rate