Health measures how much damage can be taken in Training.
Wizards with Training Proficiency 0 start with 7 HP. Each Training Proficiency level increases maximum HP by 1.
If a wizard's HP is depleted to 0, the wizard will be sent to the graveyard and Training Proficiency will be reset to 0. While in the graveyard, the wizard cannot participate in gameplay (training, staking etc) until revived with a Phoenix Down.
Items can be earned in Training which revive, restore or protect Health: