L. Boss Battle - Zeus
Ok, this is it - the big one. First off, Zeus grows massive and starts lobbing Furies at you. Killing them is the key to victory, and a great tactic is to either juggle them into the air (helping you avoid most of the secondary attacks Zeus throws at you), or use your Quake magic to make them soft enough to finish off. After you kill a handful of Furies, you'll see Zeus reel back, then slam his hand into the ground. Bash his fingers, and he'll withdraw his hand, letting you climb up his body and go into a Quicktime sequence. Get it right, and he'll shrink down to your size.
This part is the toughest, so be ready. Zeus comes at you with the sword, and with lightning attacks. Use the Golden Fleece to throw his bolts back at him, and this'll give you a quick health boost. Use your Quake attack and Rage to take his health down. Don't worry about running out because once you reach the next part, you'll recover most of it. Once the circle appears above his head tap Circle and get ready to hammer Circle quickly, as you rip the sword from his grasp.
Now you have the sword. Watch out for his lightening bolts (deflect them where possible), and get stuck in with combos, Rage and Quake. Eventually, you'll be in a position to perform a Quicktime event that lets you smash him against a pillar. Once he's down, pick up the pillar and break it over his skull.
He's back up again, so keep fighting. He'll take the sword back (don't worry - it's meant to happen), so you'll have to repeat the process once more. Batter him until he gives up the sword, then batter him with the sword. You'll finally fling him into another pillar, and get the chance to drop a whole block of rock onto him. After that, he goes large again, and attacks you with a sheet of lightening. Hammer Circle to stay alive, and you'll go into a cutscene. Here comes another Quicktime sequence! Importantly, once you've nailed his hands to the rocks, you'll need to press Circle quickly - so have your fastest finger ready. After this, you're treated to a cinematic. Looks like you've won. Or have you?
LI. Loom Chamber Redux
You're back in the Loom chamber. Save the game, then repeat the time travelling sequence again. Now you've reached the end. Congratulations, get ready for "The End Begins."