Hi to everybody i am new here.
I have discoverd the "KIlling Strike talent".Can oponent Evade the attack by using a fate point or it is completly unavoidable?

No, once Killing Strike has been used the attack can't be evaded.

As the description says it can neither be dodged or parried although it can miss. IIRC you spend the fate point BEFORE the to-hit roll which means there is every possibility that you waste it.

it can also get wiped out by a protection rating, such as that from a storm shield. There is also the possibility it will do no damage, or that someone else will throw themselves in front of the attack and take the hit instead (such as someone using the Marines Errant defensive mode ability), though someone doing so would still be unable to dodge or parry.

What you *can* do is burn a fate point to survive if the attack would otherwise kill you. That's about the only way that a fate point would come into the equation. Note that with fate points, you can *only* perform the actions detailed on page 204 of the main rulebook, unless something specifically allows you to do other things with it, such as is the case with Killing Strike, or advanced specializations (such as black shield), or if the GM specifically allows you to do so. Those things, for completion's sake, are below:

- Reroll a failed *test*. Note that this is exclusively for tests, which are when you are rolling against a characteristic. You cannot reroll protection rating effects, or psychic phenomena, or the number of insanity points gained when gaining 1d5 insanity points, or damage, or anything else. Unless it's a d100 roll which is being compared to a characteristic, you can't reroll it.

- Gain a +10 bonus to a test (chosen before the dice are rolled), or a bonus degree of success on a test (chosen after the dice are rolled). Note that the same limitations as above apply, and that the bonus degree of success only applies if there was success in the first place.

- Count as having rolled a 10 for initiative.

- Remove 1d10 damage (this cannot affect critical damage, so if you have a player in crit damage, they cannot use fate points to heal. Note that a character in crit damage also is only healed 1 point by first aid, and after healing that one point, they are ineligible for further healing (due to treated wounds rules, see the errata). So, if a player has more than 1 point of crit damage, they are unable to be taken out of crit range through any effects until after the completion of the mission, and the use of extended care.

- Instantly recover from being stunned

- Enter Squad Mode without a cohesion test

- Gain +1 rank for the purposes of a solo mode ability (such as one with a duration or effect based on rank, or which improves at a certain rank).

- Remove 1 level of Fatigue.

That's it! If it's not on that list, it can't be done, barring special abilities or GM fiat.