In The Broken Tower, Carthalo the shaman is supposed to help the adventurers by calling the murdered Greydog’s ghost, but he doesn’t seem to have any summoning spells like Summon Ghost or similar. I could of course handwave the thing, but to understand the shamanistic process, can he do that without any spells, and are those summon spells more for common adventurers, and shamans can manage without them?