X-Blades

Every time you enter one of the following rooms immediately make a manual save (just in case you should mess up so you can reload). The levels you want to do are the following ones (in order of playing through the game):

*) Deadly Passage (no enemies here)

*) Fork in the Road (grab the crystal in the middle and start to concentrate on the fireball shooting enemy next to the statue, the other ones will come by, you only need to mash X-button and if you have enough rage use earthquake or other stage covering spells)

*) Blades of Death (also without enemy spawn)

*) Blades of Death evening version (same as above)

*) Deadly Passage (also same as above but this time you need to watch for the level as your route to the final boss will not be through this level; just take when you are on the "Fork in the Road" level the second time the right door and fight your way through the follwing room which is the one where you had that annoying needle field the first time and go through the next door)

*) Underground Hall (you can kill the boss without ever leaving the corridor you start in and he cant touch you while you wait in there; just time the button combination x,x,rt correctly and he should go down on 5 shots)

*) Finale (once the cutscene finished press immediately back euqip light spell to a button of choice and also light mode, then buy rage max item to fill your bar and once you quit this menu activate light mode and start to spam the button you put the light beam attack on, you wil be able to trigger Jay in an endless loop if you keep on pressing the assigned button and refreshing your rage bar with more items every time it runs out)

Basically i mentioned 7 levels here as like stated above you might miss out Deadly Passage the second time (like i did). Also the last two levels are great to flawless victory a boss.
NOTE: YoshiMiyamoto has another nice idea of how to handle the Fork in the Road level just check out the comments (credit goes to him of course)

There are 4 levels in the game you should make sure that you complete with zero hits taken.

1. The room with the falling blades
2. The room with the spinning blades
3. The room with the spinning blades (evening)
4. The room before the final boss where you shoot the one monster without leaving the corridor you start in.

If you need two more levels after beating the game, start up a new game on Easy. To beat the first two levels of the game without getting hit, constantly purchase Rage (it only costs 1 soul).

On level 1, shoot the first set of dinos from afar. Then when you get earthquake, buy rage and use earthquake a few times. Buy rage again on the ice enemy to take him out quickly with fireballs.

Level 2 is easy enough with constant running and blasting fireballs when given enough room.

1-2 : Easy one, in this game you have 2 rooms without monsters -> only some jump so you can get no damage if you want.
3 : The first room in the game is really easy in easy mode, kill some mobs with your guns and aoe (and don't forget to buy enough mana, only cost 1 :p)
4 : The first boss, just use fire spell when you run and buy mana (it will unlock another achievement).
5 : After the first boss you have good place to do it too, they only come from one way, buy mana if you want and use your guns.
6 : The last room of the game (before the final boss), you have only one monster to kill ... and it's pretty easy to do it.

You can do this achievement everywhere ! If you get 0 damage in 2 rooms in hard mode and you try to do it in easy mode, don't try to do it in the same rooms (it won't work) but they'll count if you get 4 others rooms in easy mode.

Hope that helps you :)