So after some campaign delays, we're near level 7 in this campaign. In play, so far, Wails from the Grave is useful to spread a little damage to a secondary target. Targets that are near death, casting a spell or riding something seem best. Used the Rune Knight' Cloud rune when the barbarian was getting hit by a blackscale (ogre-like) lizardfolk and the wizard was being grappled by a kobold. Attack squashed the kobold, freeing the wizard who magic missiled the lizardfolk. Saved the barbarian getting hit again. Less useful when there's a solo enemy but still a rogue.