I recently got a tip from a reader (Thanks Meh!) that WAR added items to the new vendor in the starting aread (and Chaos Wastes). At first, these vendors allowed you to purchase a boost up to 30/40. But with a couple of weeks left, they added two new potions.
This one bumps you up to RR100! It also gives you 2,500 War Crests to help you gear up. It only costs 100 War Crests. If you don't have 100, 10 War Crests will get you a potion that makes you 40/80.
I'm not sure I'll use the RR100 potion. I made it to RR84 on my Engineer and I am fine ending the game with that.