You can unlock Healer Mode by actively healing other party members in battle. More specifically, each character needs to heal other party members between 70-200 times before this mode is unlocked for them (the total number will vary with each character).
When set to Healer Mode, characters in your party can fill up their Overdrive gauges by healing allies in battle. This occurs from using healing magic, and from the use of items like Hi-Potions and Al Bhed Potions.
You’ll receive a notification in battle as soon as a character learns an Overdrive Mode. Then after the battle you can go into the “Overdrive” section of your menu and set the mode you want for each character.
Learning Healer Mode
Each character will have a set number of turns fulfilling an Overdrive Mode’s condition in order to learn it. In the case of Healer Mode, you’d need to spend turns healing allies to unlock it.
Here’s a list of how many turns each character needs to spend healing in order to learn Healer Mode:
|Healer Overdrive Mode Unlock
|Number of Turns Healing
Keep in mind that the conditions for learning Healer Mode are slightly different from actually triggering it. Since learning the mode keeps track of the number of turns spent healing, restoring HP for multiple allies at once will still only count as one point towards your progress.
Using Healer Mode
Characters using Healer Mode will fill their Overdrive gauges based on the amount of HP recovered. This is calculated for each ally that is healed.
This does not include the character that is doing the healing.
In other words, when using items or abilities that heal the entire party (like Pray and Al Bhed Potions), you’ll see the Overdrive gauge increase twice in one turn.
This mode is best suited for characters who like to focus on healing and support, like Yuna and Rikku during the middle portion of the game.