Control of topological states of DNA by transient breakage and subsequent rejoining of DNA strands. Topoisomerase II makes double-strand breaks (By similarity). Essential during mitosis in the adult germline and during embryogenesis for proper segregation of daughter chromosomes (PubMed:20116245, PubMed:23684975, PubMed:27707787). Required for centromere resolution during mitosis (PubMed:18202360). Required for chromosome segregation in anaphase of meiosis I during spermatogenesis (PubMed:27707787). Promotes cleavage furrow stability during cytokinesis upon the presence of chromatin obstructions (PubMed:23684975). Promotes DNA break formation upon zygotic genome activation in the Z2 and Z3 primordial germ cells in L1 larvae, thereby activating a checkpoint response (PubMed:26073019). Essential for embryogenesis (PubMed:18202360). ATP-dependent breakage, passage and rejoining of double-stranded DNA. Binds two Mg(2+) per subunit. The magnesium ions form salt bridges with both the protein and the DNA. Can also accept other divalent metal cations, such as Mn(2+) or Ca(2+). Homodimer (By similarity). Interacts with nmad-1; the interaction is required for localization of top-2 to DNA (PubMed:31283754). Interacts with gcna-1; this interaction allows the resolution of topoisomerase 2 DNA-protein cross-links (PubMed:31839538). In the hermaphrodite and male germline, localizes to the nucleoplasm in the proliferative mitotic zone except in metaphase where it localizes to the spindle. In the transition zone, associates with chromosomes and localizes along the length of chromosomes in pachytene nuclei. In diplotene, starts to relocalize to the nucleoplasm. In the oocytes, it is completely disassociated from chromosomes in diakinetic nuclei. In the male germ line, it is mostly nucleoplasmic in karyosome nuclei. In male meiotic metaphase, surrounds chromosomes and a small pool is detected in the cytoplasm. In meiotic anaphase, encircles the chromosomes and localizes between the segregating chromosomes. May co-localize with nmad-1 on DNA (Probable). Expressed in the hermaphrodite and male germline. RNAi-mediated knockdown results in embryonic lethality (PubMed:18202360). Disrupts proper hcp-3 localization on mitotic chromosomes indicating unresolved kinetochores and inhibits centromere resolution (PubMed:18202360). Causes a chromosome segregation defect during the first embryonic mitotic divisions without affecting cytokinesis (PubMed:20116245, PubMed:27707787, PubMed:23684975). Leads to increased localization of the condensin component capg-1 to the spindle midzone and the midbody and to chromatin bridges with enriched levels of capg-1 (PubMed:23684975). Increased levels of phosphorylated air-2 at the spindle midzone, indicating activation of the abscission checkpoint (PubMed:23684975). Leads to cleavage furrow regression and failed cytokinesis during the second embryonic division (PubMed:23684975). Results in lack of rad-51 foci formation which are indicative for DNA damage in Z2/Z3 primordial germ cells and leads to premature cell-cycle reentry of the Z2/Z3 cells in L1 stage larvae (PubMed:26073019). Eukaryotic topoisomerase I and II can relax both negative and positive supercoils, whereas prokaryotic enzymes relax only negative supercoils. Belongs to the type II topoisomerase family.