Here's an idea:
Fourth hero, with at least these abilities:
Potions: Phodom + Fradz + Galeoth (totally of 6 abilities)
1) Drink Health Potion For Phodom - Drinks a health potion, starting from lower ranked potions to high ranked ones. If the drinker doesn't have health potions, can use restoration potions(heals both health and mana)
2) Drink Mana Potion For Phodom - Drinks a mana potion, starting from lower ranked potions to high ranked ones. If the drinker doesn't have mana potions, can use restoration potions(heals both health and mana)