'Engku' is the great being of the underworld waters, conceived as a dragon or serpent dwelling beneath the earth. In the paired cosmology best described for the Temiar, it forms a complementary opposite to Karey: where the thunderer strikes from the sky, 'Engku' answers a broken prohibition from below, dissolving solid ground into mud and raising the waters that can drown and overturn the world. The downward portion of the blood sacrifice - blood mixed with water and poured toward the earth - is its share. Its identity is genuinely unsettled in the literature. Some Semai use the name Ngkuu' or Enku for the thunderer himself, collapsing the two powers into one; others keep them distinct as an above-and-below pair; and 'Engku' is regularly identified with the world-bearing serpent whose movements cause earthquakes.