I don't have an Elder Guardian in my game, I sometimes play in Peaceful mode, sometimes I use Easy Mode, it seems that in Peaceful Mode all the Elder Guardians will be cleared, so how do I get The Deep End achievement.

The next question is, the official does not allow it to respawn, what is the point of doing this, and will the Elder Guardian drop any valuable items after killing? It doesn't seem to be, so why can't the Elder Guardian respawn?