Pallbearer’s third album stretches the Arkansas outfit’s brand of doom metal to mountainous new heights. More polished—but no less punishing—than Sorrow and Extinction or Foundations of Burden, Heartless is a gleaming bulldozer of a record, shifting effortlessly from the operatic melancholy of “Cruel Road” to “A Plea for Understanding,” which blows out the spacey grandeur of Pink Floyd to nearly 13 minutes.