Many spells require incantations and concentration to enact. Some even require meditation or even trances. However, there are plenty of spells that take only a moment, a word to use and wield. Most of these are basic spells, at best, but there are a few powerful ones that take but a word. The more apt and practiced you are, the less concentration it takes to use a spell.
Lamia- a Greek mythological female demon. Half-woman and half-serpent, she was described as a child-devouring murderer. Lamia were the daughters and granddaughters of Lilith... who bore the succubi, who bore the vampire.