Defeat the Balrog as Gandalf in the Mines of Moria ("War of the Ring" Campaign).

Beat the game

Solve the Three Judges

Collect all of the Phoenix Feathers

Save Pandora

Acquire the Boreas Icestorm

Kill Cronos

Gut 3 Centaur Generals

Kill the Poseidon Princess

Kill Hermes and acquire his Boots

Cover Kratos in 500 buckets of blood by killing the enemies

Kill Hades

Upgrade any weapon to the next level