Is Four Face Buddha a very powerful Buddha?Why is he so effective in granting wishes to those who ask for it ?

Powerful buddha to do what? If he is powerful, he will not be buddha. Budda means he is a understanding, really know what he is doing , no mistake, no regred and understand what karmas will be. 4 Face budda is come from Tibat or Ancient India who was a Granyin buddi wished to save people from his mercy wishes. But he is god not budda. He still angry when people are not obeydience and follow him. A budda will not angry. 4 face budda will have a Amita on top of his head to stop his anger.