В ДАМКАХ collPrepPInvarsubj-compl with copula (subj: human, usu. pres) one is in an advantageous position, one is a winner
X - в дамках - X has it (the game) all wrapped (sewed) up
X is sitting prettyitfc in the bag (for X).
Пленных не брать! Вот так! Раз, два и в дамках! Современная война - стремительная штука! (Аксенов 6). Take no prisoners! Just like that. One, two, three and it's in the bag! Speed is the essence of modern warfare! (6a).