Originally Posted by
Tesiqurasa
When done correctly, you're not always losing HP. Teleport through the mobs, not directly into them. As a priest it should be of no consequence anyway. To effectively train, you should be actively moving about the map (teleport). Level 1 telemastery allows you to damage mobs while doing something already standard; it's not meant to be used as your only skill. Unless you do not want monsters aggroed or stunned, tele-mastery should be on. It's an incredibly useful tool and makes Priest training more tolerable.
Beyond that, even just 1 point into the skill makes it very effective. It does not have a set duration, but instead acts as a toggle skill. A priest above lvl 80 with no telemastery is a priest who messed up.