There are a total of 8 Phantasm skills linked to mesmer weapons (Greatsword, Staff, Sword Offhand, Torch, Pistol, Focus, Trident and Spear) with a further two Phantasms available from utility skills (Phantasmal Defender and Phantasmal Disenchanter).
Each Phantasm has its own role to play but they all tend to come down to one thing: dealing damage and lots of it. Like Illusions, Phantasms are temporary summons that only last as long as your target is alive or until they are killed. Phantasms can be easily identified by the fact they are a transparent and pink in colour and tend to have a unique appearance based on their role. For example, the Illusionary Duellist wields twin pistols. Just like Illusions however, Phantasms have very little health and can be killed incredibly quickly. Ensuring you use them at the right moment is key to maximising their damage.
I’m undecided as to whether or not I like the Defender. On paper, no one could deny it sounds excellent. In reality, I’ve struggled to make it work. The fact that it causes a buff to all party members around it (Illusion of Defense) that redirects half of all incoming damage can be incredibly useful. What I dislike the most however is the fact that its cast time is incredibly long (around 4 seconds) while it dies incredibly easily as a result of running into the thick of action. What I would like to see is the Defender simply stand next to the mesmer and attack anyone who comes near so that suicidal tendencies are removed and you actually stand a chance of utilising its damage mitigation buff. With such a lengthy cast time, it also makes the skill impractical in the heat of battle as you’ll undoubtedly receive a huge amount before it even comes into play. Would I take this over other utility skills? Never in its current form, though I have used it in some PvE boss encounters but even then, I wouldn’t recommend it.