One use only. The Moon Staff of Lileath can either be used at the start of any of Teclis' Magic phases, in which case a bonus power dice is added to every casting attempt Teclis makes that phase (you still need to use at least one dice from the power pool for each casting attempt), or if Teclis suffers a Miscast (declare you are using the Moon Staff of Lileath before rolling on the Miscast Table), in which case the result of the miscast is ignored. In either case, Teclis’ Strength and Toughness are both immediately reduced to 1 for the rest of the game.