Shackles of Hyperion

Head through the cave here, defeat the soldiers and archers, and flip the switches. That will let you climb the cliff nearby to reach another switch, which will free Hyperion's head. With that done, drop down to where the two switches were located, then run towards the now-open wall to reach Hyperion. A short cutscene plays, after which you can move on via the cliff to the next save point.

Chains of Atlas

You'll come to a crank-pulling game here; you have to turn the cranks so that you can reach the far end of the chain, but enemies will appear and attempt to attack you, which will cause the gear to start moving backwards. It moves backwards fairly slowly, so as long as you kill your enemies in short order, you should be fine. Try either throwing them off or using your charged square attack with the Gauntlet to knock them backwards off the ramp. With that done, you'll need to punch the little spike near the end of the chains to reach a cliff leading out of Tartarus.

The Dock of Charon

Fight off the enemies in the trap room here and move down the path towards Charon's dock. Save your game, then use the Gauntlet to bust through the gate and move on to Charon.

Boss Fight: Charon

Charon is back, and this time he's a bit meaner than he was before. He has multiple phases, each one separated by another by another jump atop his health-regeneration platform. This time, though, you can prevent this process from taking place.

Phase One

This phase is basically identical to the one that you went through earlier. Charon will use his scythe attacks, then switch to flinging balls of energy at you. Use regular attacks on Charon (as opposed to holding the L button for combos) so that you can quickly block his attacks or dodge away as necessary. When he starts flinging orbs around, don't dodge them this time; reflect them back to him with your shield by tapping L just before they connect to you.

After Charon hops aboard his little pedestal on the eastern edge of the arena, run over so that you're underneath him, switch to the Gauntlet, and quickly use a charged attack on one of the pillars beneath him to break it and prevent him from fully refilling his health.

Phase Two

This phase is much more difficult than the first, since Charon will begin using his powerful magical attack on you, Charon's Wrath. If this hits you, you'll be locked up for a few moments, take damage, and be prevented from attacking or moving, allowing Charon to hit you. You must dodge most of these attacks, or you'll be significantly weakened in this phase. It's best to simply stay away from Charon as best you can, watch for his beginning animation (which looks like he's sucking up his breath), then dodge to either side. Alternately, if you're up close to Charon, you can dodge in his direction, which will probably send you rocketing off behind him, allowing you to dodge this attack. Again, just use normal attacks here; if you use a combo, like Cyclone of Chaos, you won't be able to dodge in the middle of it and will almost always be hit by Charon's Wrath, which hurts.

If you're having a hard time keeping your finger on the L+R buttons and also using your thumb to move around (it can really hurt your hand!), try placing the bottom of the PSP up against your chest and using pressure from your hands to hold it in place.

Phase Three

Charon stops using his breath attack, thankfully, and resorts to warping around the arena and smashing his scythe into the ground. This will cause mini-explosions that will deal no damage if you're either far away or jump over them. After two of these mini-explosions, a larger one will occur in the center of the arena. You'll have to jump over this one, but if you do, you'll be able to whack on Charon for a good length of time before he can counteract. He'll also throw orbs at you, but these can be reflected for health.

Phase Four

After the impaling of Charon at the end of phase three, he'll launch himself into the air and fling orbs at you from up above after you attempt to grab his mask on the ground. These orbs move much more quickly than they did before, but you'll still need to reflect them back at him. After he falls from the sky, start the minigame again to finish Charon off.