Heinald's second achievement was his experiments on the potion called Shied of Fire Heart. He gathered the materials he thought might be compatible with this potion and as a result of various experiments he carried out, he added an essence consisting of a mixture of Elir Flower Leaf and Juirus Seed to the potion's formula. As a result, he managed to increase the immunity rate against fire that potion provides to the person consuming it by 5%, increasing it to 20%. However, the addition of this material slightly increased the impurity rate of the formula.