Dragon Valley 4-15 is certainly one of the more challenging levels of the game, especially for lower level dragons. Luckily, there are a couple of tricks you can use to make your dragon last longer in this level. It will help you if you have Crystal for this level, but you can certainly use any other dragon it will just take longer for you to beat the level.
To start, move your dragon down the slope to the right so you are right on top of the Dragon Faerie. Use volley to damage both the ground below you and the Faerie. It will probably take you a couple of turns to take him out, so be prepared to take on some damage yourself. The good part about being over here is that the bouncy bombs from the Jumper will bounce over your head and miss, and the Fire Bomber won’t be able to hit you with the angle of his attack.
Once you have blown a hole in the ground, drop down. If the Faerie is still alive, take him out now from below. Your next turn should take you just below the Jumper. Use Ice Cube if you have Crystal, as both the initial attack and the ice cube will do damage to the enemy above. If you’re using any other dragon, use quickshot, cracking, or just Power to do enough damage without breaking the floor too quickly. If you do happen to break a hole in the ground, make sure you move away from it so their attacks can’t drop down below and hit you.
Using this method should help you beat this level. Keep in mind, if your dragon level is too low, you might now have enough Hit Points to sustain the first 1-2 attacks you will take on from the Dragon Faerie plus the damage from the fall you will take. You might just have to level your dragon (which can be done rather quickly by farming 4-14) or embed some higher level stones to pass this level. Don’t worry, once you do, the next levels won’t be quite so hard.