yeah i've the same problem
i found that u cant use #1 and #7 at the same time, otherwise u'll be kill instantly by any mob
just tried #1 alone and it doesnt quite work, the red hp bar stays max but when the blue hp bar drops to 0 and ur dead
same for #5
but u can turn #5 off, use the X button skill then turn it back on again
so you still die with the option on? the moving 'bar' actually is just the game graphically displaying catchup to the real health, which remains at 100.
i've never been killed by anything with the no damage option on