Enemy Aggro Indicator

Tired of not knowing when enemies will de-aggro from you? You can now see when you're too far from an enemy! A green bar will be shown over enemies' health bars, indicating how close they are to de-aggroing. When the bar fills completely, the enemy will lose interest and go back home.

To turn this feature on or off, go to Start -> Option -> Advanced -> UI Options -> Show Monster Distance Indicator.

This can be really useful for kiting or making sure you're not dragging bosses too far.