Mystic Theurge

Publisher's blurb:

This archetype allows spellcasters to gain extra spellcasting variety at the cost of class features by learning spells from other classes. Also included is a new feat that any spellcaster can take, which allows them to combine weaker spells into a stronger spell slot. Finally, a brief accompanying article discusses the history of mystic theurges in Rogue Genies Games’s Blood Space Campaign Setting.