darks adrks draks rdaks ardks radks dakrs adkrs dkars kdars akdrs kadrs drkas rdkas dkras kdras rkdas krdas arkds rakds akrds kards rkads krads darsk adrsk drask rdask ardsk radsk dasrk adsrk dsark sdark asdrk sadrk drsak rdsak dsrak sdrak rsdak srdak arsdk rasdk asrdk sardk rsadk sradk daksr adksr dkasr kdasr akdsr kadsr daskr adskr dsakr sdakr asdkr sadkr dksar kdsar dskar sdkar ksdar skdar aksdr kasdr askdr sakdr ksadr skadr drksa rdksa dkrsa kdrsa rkdsa krdsa drska rdska dsrka sdrka rsdka srdka dksra kdsra dskra sdkra ksdra skdra rksda krsda rskda srkda ksrda skrda arksd raksd akrsd karsd rkasd krasd arskd raskd asrkd sarkd rsakd srakd aksrd kasrd askrd sakrd ksard skard rksad krsad rskad srkad ksrad skrad
Note: these 'words' (valid or invalid) are all the permutations of the word darks. These words are obtained by scrambling the letters in darks.