Bayeri is good for shadow element monsters and has good max HP. However, that is easily overshadowed by the fact that skills can be interrupted when Bayeri takes damage, making it inefficient. It is quite possibly the least functional Homunculus S.
Bayeri contains the German word "bayer" which means "Bavarian." The word "bayeri" itself is used as a binominal nomenclature for marine gastropod mollusks.