When using /back in game it teleports you to your last location. Just say I was at my base then died, after I died I warped to wild or something. When I spawn at Wild I will do /back and it will not teleport me to my most recent death location, simply just teleports me to my last location. On the website under all ranks it says "ability to use /back (teleports you to your death location)". I think this should be changed to stop further complaints/confusion.
I think that descriptions assuming it's most useful when you die...... so you can do it to return to where you died. But yes - it takes you back to the last location you teleported to or from. We'll change up the descriptions to make it clearer when we get a moment.