In PVP, focus on your Shield (SD) potions. If your SD hits zero, you become extremely vulnerable.
If you are playing on an older private server or a "97d" classic version, the MU Helper might not exist. In these cases, players often use keyboard macros. auto pots mu online work
These are the default keys for Health, Mana, and SD potions. In PVP, focus on your Shield (SD) potions