Fusion is a special kind of invocation, which use weaker monsters to get better. Only a few monsters are available for this type of invocation and there are some rules to follow. Monsters 4 stars need four monsters 4 stars maximum level (30) and awakened, and these three monsters 3 stars (natural) and a 2 stars. Now for the fusion of a 5 is necessary four monsters 5 stars maximum level (35) and awakened, they are three 4 stars (natural) and a 3 stars. Monsters 4 stars for this merger are also available as fusion.