This is op, as it dupes your whole inventory. Ez levels with grindstone guaranteed. Doesnt work on multiplayer, so dont get your hopes up. could be used in speedrunning lol
How to do it:
1: Build a nether portal
2: Die inside the portal (IMPORTANT FOR DUPING WHOLE INVENTORY)
3: DON'T RESPAWN! IT WILL RUIN IT! Instead, close the game with Task Manager.
4: You should spawn in the portal with your items after you reload the save. Now, go to the overworld.
Your inventory should be waiting for you in the overworld. You could fill your entire inventory with Enchanted gear and get XP on a grindstone.
I'm gonna try it again on another world. If it works with any death kind, i will edit the thread.
Test it out on different pc's for me, it could be luck moment...