If you want TBN on GNB, get your DRK to use it on you. Otherwise, no, you can't have it.

From a lore standpoint, "The Blackest Night" is a quoted line from the single best written job quest in the game, invoked by your memory of two dear friends. Written by the very same writer who was responsible for the main scenario for this expansion, in fact. From a gameplay standpoint, it's the reason why DRK is a defensive powerhouse, and it's going to be a massive asset in prog. You can keep your low effort 'big' dps numbers.

In your darkest hour, in the blackest night… think of me… and I will be with you...

...Always.

For where else could I go? Who else could I love but you?