Once you get a character to level 250, you can opt for a Rebirth. You can only rebirth 3 times.
This will happen to your character:
This gives you the following advantages:
You can buy exclusive items:
Here's the thread where rebirthing was discussed
Before rebirthing, make sure to leave all your equipment and backpacks in your Depot Locker!
You will go from level 250 to level 8 so your capacity will be decreased and your level-dependant equipment will not be available.
Your Stamina will get back to 42:00 so don't waste a Scroll of Stamina at level 249 if you don't have to.