If I atack with the Enraged crewman and the hemmerhorn raiders:

Enraged crewman: Melee. If you win a challenge in which Enraged Crewman participated by 4 or more STR as the attacker, the challenge is considered unopposed.

Hammerhorn raiders: Army. No attachments. While Hammerhorn Raiders is attacking, raise the claim value on your revealed plot card by 1 if you win the challenge by counting at least twice as much STR as the defending player.

and i have a total STR of about 12, and my opponent defenses with 7, the challenge is considered unopposed because of the enraged crewman.

That implies that the defensing STR is considered to be 0 because the chalenge is unopposed, and the hammerhorn raiders's habilitty of rising the claim becomes active?? Or it is considered an unopposed challenge but the balance of str is still 12vs7, so the hammerhorn riders would not become active?

The challenge is considered unopposed for the purposes of anything directly related to unopposed challenges (the power, passives, responses), but it doesn't actually modify the opponent's strength total. You still haven't counted twice as much strength as your opponent, so Hammerhorn raiders don't raise the claim.

Put another way, a challenge in which your opponent counts 0 STR is considered unopposed (as per the rules), but a challenge that is unopposed does not necessarily mean your opponent counts 0 STR (in the case of Drumbeater or Enraged Crewman).

Ok, thanks for the answer!

I supposed that, but I wanted to be sure if I was missing a great combo.