can someone explain me how work this skill? sometimes it restore my own hp sometimes not.... one of my frs told me u must be 30% hp and it restore but i tryed and sacrifice work when it want? zomg?

You can use it when you have enough HP to "sacrify", I mean it doesn't consumes MP but HP.

With Sacrifice skill you heal your target, that means you can heal anyone even yourself, but when you use this skill, it takes away a fixed amount of your HP. So, if you use it on yourself, you'll lose HP (skill requirement) and then be healed (skill effect). If you cast it on anyother target you will only lose HP (ppl use this skill in pvp servers to get hp into 30% and then activate AI)

if you don't have any buff that increases m.attack or increases the healing you recieve, the HP restored should be almost (if not equal) to skill's power.

If you want to use it to heal yourself, you have to increase your healing power, m.attack... and ofc cast it on yourself

P.D.: maybe you wanted to know about "Touch of Life"

soo i can`t trust sacrifice in critical moments for my own hp?

or you can wait on critical hit from sacrifice, u will have almost fully restored hp, that annoying when fighting pala
with armor/buff with heal increase if restore your hp ofc
but watch out on pvp, I saw few nobs (1 even is hero lol...) that use sacrifice and forget to target himself so he heal hes enemy on olympiad QQ