Thrall of Protection

 is an active skill that can be taught to Mystics at level 50. It can be ranked up at later levels.

Rank table
To upgrade Thrall of Protection to the next rank, one must find a Magic Instructor, Mystic Trainer, or from the Skill Menu 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, 55 at level 65, and 60 after apexing a character available to spend on all available Mystic glyphs. Most glyphs, specifically common glyphs (green glyphs) can be found from Sabex Armory, Macellarius Catacombs, or can be obtained via Glyph Tokens gotten from the Quartermaster in Highwatch or from LX Tokens, while rare glyphs (blue glyphs) can be obtained by doing Vanguards for the Island of Dawn BAMs or from Guardian Legion reputation points.

(Disclaimer: You can no longer buy glyphs with currency they must be obtained via Vanguards or from Dungeon Crates.)