Ring of Pain

Dying 250 times doesn't really require a guide, as you probably get this naturally while playing through for all of the other achievements.

However, I just wanted to point out that the award (or punishment, maybe?) for meeting the requirement is unlocking the epic (purple) item 'Rebirth'.

'Rebirth' is a necklace item that allows a one-time resurrection. This can be helpful if you finding yourself dying in unlucky situations (like being rushed by a group of explosive enemies) rather than dying due to insufficient setup.

If you think this item might be beneficial to you, you may wish to expedite your dying to unlock it.