Malphas appears as a crow. He specializes in construction, and can build houses, towers, fortresses, etc. at the behest of the summoner. You want it, he'll build it: ahead of schedule, under-budget, and of top-notch quality. Simple as that! He also has the power to reveal an enemy's thoughts and desires. He accepts sacrifices, but will play anyone who offers one for a fool.
A female crow-witch in Castlevania: Lords of Shadow is named after Malphas, but she has a totally different background and nature.