The inscription can be translated as follow:
Bzad-pa'i-rdo-rje made the next verse corresponding the wish of (the family of) Sar-ma-ba's on the feast-day, which coincides with the 'State-cathedral' of Lhasa:
May Padmasambhava, king of the magicians (and) the mighty, the wrathful sovereigns, the protectors of wisdom and the magical instruments, together with their irreconcible and undivided oath and wisdom, grant the supreme and ordinary magical powers.
May he, who transformed the five personality agregates and purified the five gifts in the (highest)spere, who became a clear Buddha in the realm of the five Buddha families, set an act, which brings together in perfect harmony all the five supernatural and perfect wisdoms.
May he, who conquered all deceptions, as well the dragons, the gnomes and demons of the west and submitted the three worlds to his power, set (us) free in the great, perfect being of the diamond of language.

See colour illustration