Quote from GoldenShadowGS
One time I noticed that when I had died and gone back to get my items, It gave me enough EXP orbs to put me to level 10. So I spent all my EXP on enchantments and then drowned myself in some water near my spawn. This time, I dropped enough EXP orbs to get to level 5. I spent them on enchanting an item. Suicided again, this time I only got to level 2. Next time, just Level 1, and after that, not even enough to get level 1.
Apparently, every time you die, you drop half as many EXP as you did before. I'm not sure what causes it to reset back to level 10 or maybe higher. It doesn't matter if you spend your skill points or not, you will only drop half as many next time you die.
The Exploit part is this. I grinded up to level 18 and enchanted a brand new diamond pickaxe and got Unbreakable III and Efficiency III. Then I chested my items and drowned myself. Respawned and instantly got 10 more EXP levels to enchant my shovel too. it got the same stats, but at level II for efficiency and unbreakable.
I'm not sure why or what triggers the reset back to getting level 10 when you die. Something for us to figure out.
This a bug in prerelease 4? because in prerelease 3 if I died by say, falling off a cliff to my doom, if I ran back to get the orbs i would only get about a skill point and a half back, even if i had over 12 skill points earned.