hi guys im new on boardgames, this Sneaky skill i dont fully understand it, can u guys explain it to me how it work,when to use it?

You can exhaust the card to open/close a door without using an action.

At all times, you gain a bonus +1 damage to your attacks against monsters who couldn't see you at the start of your turn. They can't see you if they cannot trace line of sight to you, corner to corner, uninterrupted by obstacles or other figures.

thankz for ur reply whitebeard, so bonus +1 damage to my attack, does i need to have LOS from my Thief too or only the mob? n i must att at the start at my turn to gain that bonus?

You have the bonus as long as you are attacking a monster who doesn't have Line of Sight to you at the start of your turn.

It does not say you need to have Line of Sight to the monster, because if you have Line of Sight to it, it (usually) has Line of Sight to you. You would have to move, then attack to get the bonus +1.

ooo so i can only use it 1 time only on my turn? or every att that the mob doesnt have LOS to me?

Considering you get two actions per turn, technically you could use it twice if you spend fatigue to move.

thnkz! really appreciate it ... bac to my quest then