Classic version of https://www.curseforge.com/wow/addons/manawarning
Overview
ManaWarning is an addon that gives a warning every now and then when you reach a certain level of Mana during combat. A similar warning is given when you reach a certain level of Health. The threshold to give a warning can be modified and set in percentages.
It also gives a warning in either party or raid chat whenever you’re going OOM (default 10% of mana pool).
For both Mana and OOM messages, potions, objects and abilities are checked for Cooldown, and a given estimate in seconds is given for when which pot/ability is (again) available.
Configuration
There is a configuration screen available through the /manawarning slashcommand.
The ManaWarning-Classic Team
