All's Well that Ends in the Well
“Hostile sylphs who would rather see the Twelveswood burn before making peace with the people of Gridania have begun using their forbidden magicks to charm the forest's creatures into doing their bidding. Temporarily enhanced by the spells, these turned creatures now possess the ability to enfeeble their victims with terrible poisons and wide-reaching attacks.
Only by slaying the renegade sylph leader Briaxio of the Well will the creatures' minds be freed.— In-game description
All's Well that Ends in the Well is a level 25 guildhest introduced in patch 2.0. It is practice for managing multiple mobs or attacking parties.
Reward: 
2,060 experience, 
140 gil
Strategy
Briaxio of the Well
After defeating 3 groups of mobs, you will encounter Briaxio of the Well, the mini-boss of this guildhest.
Through the fight, this sylph boss will spawn 5 groups of adds. Crowd control and kill the adds as soon as possible. Briaxio will also cast debuff abilities. Be sure to have your conjurer remove these debuffs from your party members with the spell esuna.
- If damage needs to be directed to adds, make sure to place damage over time (dots) onto the boss first before redirecting damage.
- Use conjurer's esuna to remove any debuffs on your party members.
Healer Mechanics
If the tank is extremely low in health and has a debuff - heal the tank once before cleansing the debuff and then use Esuna on the tank. Top off the tank as much as possible as damage can potentially add up quickly in this fight.