So basically, with an 80 pally you can become invincible
step 1: level a pally to 80 and get 2492 mastery, it is the updated cap that you need!
step 2: once you hit 2492 mastery the game gets confused about how much damage you take making you take around 0 damage per hit and hitting 100k-1 mil damage
UPDATE: The damage is patched! But the invincible part is not!
skip to 0:53 to see please note this is not my channel or video
read through the comments! If you need help answers will mostly be there!