Instructions
Play through the first chapter until you reach the boss battle with the Swamp Troll. This monster will pick up tombstones and attempt to hurt you with them, and it will also lift both fists into the air before it does a ground pound attack. Dodge the swinging tombstone attack and press "X" to jump just before the troll punches the ground to avoid the ground pound attack.
Attack the Swamp Troll after you've jumped to avoid the ground pound attack by pressing either "Square" or "Circle." You can hit the troll a few times while you're still in midair; he won't be able to reach you. Press the "L2" button to either block his attacks or roll out of the way. Attack the troll immediately after every block and dodge -- that's when he's most vulnerable.
Press "L2" to dodge the Swamp Troll's charge attack. You'll see this coming -- the troll will stand still and lean forward before he charges. Attack the troll from behind after you dodge this attack. Keep attacking the troll while countering and dodging his attacks until you deplete his entire health bar.
Press the "R2" button when you're prompted to begin the button sequence necessary to finish off the Swamp Troll. The exact sequence changes every time you play, but if you press the buttons as they appear on the screen, you'll successfully defeat the troll. If you miss a button, attack the troll a few more times and you'll receive the prompt to press "R2" again. This will start the button sequence over.