Can you use non-AP costing special abilities when it's not your turn?

[Lemminkäinen]

Basically what it says in the title.

Can, for example, Sister Alena use Blood Prayer when someone declares an attack against her to pump up her CBT, declare a Response reaction and then make the opposed CBT roll with her new +2 CBT score?

Edit: hmm, while checking out some cards I sorta started wondering - is it that if the ability has the hourglass symbol, then you can use it at any time you want but if it has the hand symbol, then you can only use it during the fighter's activation?