Complex sentence: Magik supports multiple inheritance, and mixins (which implement data with no instantiation) and new instances are made by cloning an existing instance (which will typically be the exemplar but does not have to be).
Split into simpler sentences: Magik supports multiple inheritance, and mixins (which implement data with no instantiation). New instances are made by cloning an existing instance (which will typically be the exemplar but does not have to be).