Thrall of Vengeance

 is an active skill that can be taught to Mystics at level 12. It can be ranked up at later levels.

Rank table
To upgrade Thrall of Vengeance to the next rank, one must find a Magic Instructor or Mystic Trainer and pay a rank-dependant price.

Glyphs
To glyph, a glyph must be obtained and learned only once. At level 60, a character has 50 glyph points available to spend on all available Mystic glyphs. Most glyphs, specifically common glyphs can be purchased from a Glyph Master, while fine glyphs must be looted from enemies.

(Disclaimer: As NPC shop prices vary depending on a variety of factors, the prices below are subject to variation. Only take them as benchmarks.)