Agents, когда я интересовался данным вопрос, то всё, что я смог найти (достойное внимания) это:
P.S. Ссылка будет позже.Icebound Fortitude (IBF) – IBF reduces all incoming damage by 20%. This percentage is modified by the amount of defense skill the DK has. It increases at an amount equal to approximately 0.143 to 0.15% per point of defense. This means at 540 Defense Skill it will increase to approximately 41%. A DK tank at 600 Defense Skill will increase IBF to approximately 50%. IBF lasts 12 seconds, more if talented. It has a 2 minute cooldown. Glyph is used for PVP.
P.P.S. Добавил ссылку.