Repair polymerase. Involved in gap-filling in DNA non-homologous end joining (NHEJ) required for double-strand break repair. Can incorporate a ribonucleotide (rNTP) into a primer DNA. a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = diphosphate + DNA(n+1) Belongs to the DNA polymerase type-X family.