Stormbringer - Michael Moorcock Here ends the saga of Elric of Melnibone.
Chaos begins to tip the balance of the world in its favour, and Elric is tasked with restoring it.
A rather introspective and downbeat way to end the series, but it fits in with sagas of old where the hero has to make sacrifices to achieve the result.

This is still my favourite book cover of all time.