Boons in Neverwinter are an interesting concept. Basically they are a way for you to keep gaining power at max level beyond upgrading your gear, by permanently adding to your character's stats and abilities. You usually get to choose from one of several boons upon completing a certain amount of campaign tasks. Some of them are fairly mundane, such as "you gain 2000 extra hitpoints", while others can involve interesting procs along the lines of "every time you get hit in combat, you have a chance of striking your opponent with a bolt of lightning".
One the one hand, this is a neat form of progression beyond merely grinding for gear, but on the other hand it's not very alt-friendly, considering that there are more than half a dozen endgame campaigns in the game by now and each one is supposed to take you about a month to complete. None of my own alts have finished more than a couple of those campaigns for example.
Cryptic does actually offer a way of catching up more quickly... but it's via buying campaign completion from the cash shop. I'm sure that those who are heavily invested in the game and enjoy running endgame on alts are grateful to have an option at all, but it is yet another thing that adds to the game's pay-to-win flavour.