Use it as a weapon. Your mages go into battle and heal minor flesh wounds on your enemies. If it succeeds the enemy isn't really better off, it was just a scratch. If it fails, one less enemy. With a fifty percent success rate your mages will be racking up kills fairly quickly.

Use it as a weapon. Your mages go into battle and heal the enemy. Fix their high blood pressure. Congenitive heart defect or heart murmur? Cure their gout. If it succeeds the enemy isn't really better off, you aren't reviving a fallen warrior. You may also be able to cast it again until you do cause catastrophic or deadly injuries. If it fails, one less enemy. With a fifty percent success rate your mages will be racking up kills fairly quickly.