I have just read ( on another message board sorry guys lol) that a slann knows his spells and that of a skink priest is this true? I did not know this if so.
The other site was probably referencing the vassal rule. A slann can use the priests line of sight when casting magic missles in the priest's forward arc. The slann can also be a loremaster of a single lore of magic through the discipline Focus of Mystery.
Yah, the only time the Slann would know the same spells as the skink is if he were Loremaster of Heavens. Otherwise the skink and slann have their own spells, with the exception that Arli pointed out.