I decided to write this brief guide in order to help dps and tanks in running instances with mystics as healers. As a mystic myself, I'm a bit disappointed when people blame me for not healing enough when they actually know nothing or very few things about my class. Since the guild is going every day in instances where the presence of the mystic is required (KN raids), I think these few tips could make everyone's life easier in these dungeons.
First of all, mystics can heal enough through every instance in the game, just like the priests, but they require some sort of collaboration in order to do it.
Mystic heals three targets with his main healing skill. This means that while this skill is used, the mystic and another party member won't receive any healing. If the whole party keeps getting hit every few seconds, the mystic job will become very hard and in hard dungeons the party will probably wipe. As many people say, the mystic is the “good players healer”, as he can heal enough as long as you're not getting hit by every boss skill. Learn to dodge or get ready to drink many potions because the mystic can't handle too many reckless dps.
By the way, the most peculiar healing skill of mystic is the Arun's Vitae Mote, commonly known as “hp/red ball/bubble”. This is an healing over time and cleansing debuffs skill, and sadly many people don't know how it works, so I'm gonna explain how to properly use it.
First of all, since the mystic cleansing skill is just like the healing one (three targets lock-on ranged skill), the mote is what you need to pick up to help the mystic removing harmful effects. For example, in dungeons like Kelsaik's Nest, the whole party will get a debuff that must be cleansed; since the mystic will target only three party members every time he uses the cleansing skill, the fourth one and the mystic himself will need to pick up motes to cleanse themselves fastly.
Also, it is a common mistake for dps and tanks to pick up more than one mote in a row. If you're doing it, just be aware that you're doing an almost useless thing and that you're wasting the efforts of the mystic. The healing effect of the mote is over time as it restores a quantity of hp every second for 7 seconds, this effect is not stackable: picking up more motes in a row doesn't restore more hp, it just makes the 7 seconds timer restart. The correct way to get healings by the motes, is picking up one mote after the previous one's effect has ended.
For a fast run and for dps races (Kelsaik, Shandra, Crucible of Flame, etc.) let the mystic buff you. The increase power buff of the mystic is called Titanic Wrath and it consists in a 35 seconds (glyphed) aoe increasing all members power by 25 in a radius of 13 meters (glyphed). A good mystic knows that the buff duration is not that long, and he will keep refreshing it every 35 seconds; since the mana cost is huge (1125 MP) all the dps should stay close one to each other as much as possible in order to let the mystic buff them all without spending tons of mana. If the dps spread and keep running around they won't probably get any buff and, even worse, they will make the mystic waste his mana and lose concentration in trying to catch them around the room for the buff.
Notice: the Titanic Wrath has a graphic bug. The glyph of spread that all mystic should use increases the radius of the skill by 5 meters, the animation of the aoe doesn't enlarge though, even when the glyph is used it keeps being an 8 meters radius circle instead of 13. This doesn't mean that the glyph doesn't work, but simply that you will get the buff even if you stay not too far from the visible circle.
Thanks for reading, enjoy your runs with mystics!