Who are these guys, anyway? And why do you need to call upon them when you cast a magick circle?
     Magick relates to both time and space. Ancient peoples divided space into the four quarters: north, south, east and west. Sometimes they further subdivided it, but the four basic directions are the crucial ones. They assigned deities to guard each of these quarters, deities to whom the power of each quarter accrued. The Lords of the Watchtower can be male or female. By invoking them we call upon their spatial powers to guard and inform our magick circles.
    Cultures represented in the invocation lists range from Asia through Europe and Africa to the Americas, illustrating the universality of the division of space into the cardinal points. You can invoke any gods or goddesses who appeal to you, but these are examples of mythologically consistent invocations:

        ANGELS
             N   Uriel
             S   Michael
             E   Raphael
            W  Gabriel

    AZTEC
             N  Mictlantecuhtli
             S  Huitzilopochtli
             E  Tlahuizcalpantecuhtli
            W  Ehecatl-Quetzalcoatl

    BUDDHIST
             N Vajraghanta
             S Vajrapasi
             E Vajrosnisa
            W Vajrasphota
    Buddhists count five directions, assigning each one to a member of the Buddha family:
        North: color: green
              negative quality: envy and jealousy
              positive quality: all-accomplishing wisdom
              sacred to: Amoghasiddhi
        South: color: yellow
              negative quality: pride
              positive quality: wisdom of equanimity
              sacred to: Ratnasambhava
        East: color: blue
              negative quality: aggression
              positive quality: mirrorlike wisdom
              sacred to: Akshobhya
        West:  color: red
              negative quality: passion and longing
              positive quality: wisdom of discriminating awareness
              sacred to: Amitabha
        Center: color: white
              negative quality: ignorance that causes the cycle of   reincarnation
              positive quality: wisdom of ultimate reality
              sacred to: Mahapratisara - Vairochana

EGYPTIAN
N  Hapy               Neith             Osiris
S   Imset             Isis               Ra
E   Duamutef     Nephthys    Horus
W Qebehsenuf Sekhmet      Thoth
(these are the four sons of Horus, who appear on canopic jars)

HINDU
         N     Soma
         S     Yama
         E     Indra
         W   Varuna

    The eight Lokapala, Hindu Lords of the Watchtowers, are each assisted by an elephant:
             East: Airavana
             Southeast: Pundari-Ka
             South: Vamana
             Southwest: Kumuda
             West: Anjana
             Northwest: Pushpadanta
             North: Sarvabhauma
             Northeast: Supratika

    Each direction corresponds to a color in India:
            North: green
            South: blue
            East: white
            West: red