Go home, that idea sucks!
To boost martyr and make him useful as a support I believe that sacrificial lamb needs to be changed to make it do damage to enemy units aswell as healing friendly units.
Considering most other heals work this way ex. demented shaman, Jeraziah, Soulreaper, Rhapsody, Accursed, Nymph, it would not seem impossible to consider, also this would give Martyr a much needed farming tool.
A consideration would be to possibly remove one of the effects sacrificial lamb to compensate with the ability to do damage with the heal.