The Illusionary Mariner is one of two underwater Phantasms, the second being on the Trident. As there are only two weapon sets underwater, it's highly likely that you'll use this Phantasm on a regular basis. Whether or not it is your favourite out of the two depends entirely on whether you prefer a ranged or melee based playstyle. The Mariner deals a series of attacks incredibly quickly (8 times in total) while also evading your target, making it incredibly powerful. With a 10.4 second duration between attacks however, you'll be fortunate to see it attack more than once before it is killed. Out of both the Mariner or Whaler, I much prefer the former simply because of its attack animation and raw damage.
read more: http://www.guildwars2gold.org/