#1. After you start the game and beat the dragon boss, Somulo, its head will pop out of the wall in one last attempt to kill you before you escape the coliseum. Just kill him for good and the HP Container will come out of the dragon's head after it falls off. This one is mandatory.

    

#2. Halfway through the first stage, you'll come to the Hippogriff boss. Beat him for the second HP Container. This one is also mandatory.

    

#3. Come back to Level 1 after you get the Buster weapon. Near the end of the stage, where the long vertical section is, there is a part of the wall that can be broken (marked by square tiles). Break the bricks with the Buster, then walk through the wall to the HP Container.

    

#4. In the graveyard area of Level 2, destroy the skull piles with the Ground Gargoyle. One of the piles that's on a high ledge will yield an HP Container.

    

#5. At the end of the graveyard, you will meet a skeleton boss, Belth. Beat him to earn another HP Container.

    

#6. Use the Ground Gargoyle to push the statues in the water area. One of them leads to a hidden cavern. Follow the path into a cavern where the lights go off and you have to relight torches to see where you're going. On the bottom left side of this area is a wall that can be destroyed with the Buster. Break the wall and then break the pot on the other side for an HP Container.

    

#7. Find and headbutt the door near the bottom of the first area of Level 3. It leads to a secret flooded caverns area. Continue to follow the stage all the way to the end and you'll find a crustacean-like boss, Scula. Beat Scula to get another HP boost.

#8. After you defeat the Flame Lord boss in the forest area, come back to the level and go to the part that had been set on fire. You'll find an HP Container floating in midair. It was behind the trees and it's now visible because they've all burned up. NOTE: It's actually possible to get this just by losing to Flame Lord and retrying the stage.

    

#9. After you receive the Water Crest, return to Level 3 and enter the door near the bottom of the first area to get into the flooded caverns. Follow along the bottom of the second area of flooded pits and break open the bricks at the end to reveal a door. Alternately, you can go all the way to the forest area with the pond and dive into the water, then swim all the way to the end to a bricked-off door. Break the bricks and enter the door.

    

Whichever route you chose to take, both doors lead to the same room - an underwater cavern with a single vase that houses an HP Container.

    

#10. Go to Level 5 and follow the main (dry) path into the temple. Along the way, smash the statues as the Ground Gargoyle, and an HP Container will pop out of the one pictured here. Note that if you do this level, you pretty much will collect this one automatically because you can't get past the statues without smashing them.

#11. Return to Level 5 after beating the Crawler boss and climb (or fly) into the area of the temple's ceiling that he fell out of. (Note: You can also do this if you lose to the Crawler and retry the stage.)

    

You'll find a hidden area. At the end is a statue you can break with the Ground Gargoyle for another HP Container.

    

#12. Return to Level 5 with the Tidal Gargoyle and dive into the water at the beginning of the stage. Swim all the way to the end and shoot the bricks on the right wall to reveal a secret entranceway. Enter and swim along the path until you reach a fork in the road. Take the upper path at the area pictured.

    

Follow the upper fork all the way to the end and break the vase for an HP Container.

    

#13. Return to the main path of the waterway after getting HP Container #12 and follow it all the way to the end. You'll reach a giant snail boss called the Holothurian. Defeat Holothurian to get another HP Container.

    

#14. Go to Level 6 and in the very first area, fly straight up as the Aerial Gargoyle and then fly all the way to the right. You'll come to a secret entranceway hovering in the sky. Enter it and follow the path all the way until you reach two side-by-side doors. Headbutt the lefthand door and enter it.

    

Inside the door is a room with a vase that conceals another HP Container.

#15. While working your way through Level 7, you will automatically come across a giant bell at the top of a long tower shaft. Headbutt it and wait for it to stop ringing. A vase will fall out and break, revealing an HP Container inside.

    

#16. Look for a small crescent-shaped lake near the northwest part of the overworld map. Land on it, and you'll be taken to the third and final head-butting mini-game. This is very hard to do, but you must win this game to get an HP Container. Bust 25 skulls before time runs out to win. There's not much I can do to help you here except say that practice makes perfect!