Elizabeth does more than fuse personas in Persona Q: Shadow of the Labyrinth. The Velvet Room attendant has her own room loaded with Jack Frost dolls where she can heal the Persona team.
Where does Elizabeth get all of her stuff? From requests, of course. Elizabeth will give players fetch quests just like in Persona 3 and reward players that bring her what she wants. Even if you don’t want to take on requests, you still should visit Elizabeth to see extra cutscenes.
Also like other Persona games, players can fuse personas collected from battles. Fused personas can inherit skills and in Persona Q: Shadow of the Labyrinth all characters have the ability to change personas. In Persona 3 and Persona 4 that was only a gift that only those with the Wild Card (read: the protagonist) had.
Persona Q: Shadow of the Labyrinth comes out on June 5 in Japan and is slated for release this fall in North America.