All original skills have invincibility frames from beginning to the end of the skill casting animations (Transformations are vulnerable to damage again after the cast is finished).
To get the skill, you must get all 5 skill book pages from Treasure Island Part 1 (Island of the Gods) and craft the box that will give a skill book to a random class. Another way is to buy the book from other players.
To use the skill, you must have a combined level of 180, and currently be level 85.
So are they RB skills? Do they have super long cool downs or what?
"There once was a boy who dreamed of being a hero. Who believed sincerely in the battle to banish darkness from a world of light... but light and darkness are equal... and where one exists so too must the other... and when the boy finally realized this he had taken the first step toward being a true hero."