Shrithe

He realized the monster meant to attack Heorot after the blue hour, when black night has settled over all— when shadowy shapes come shrithing dark beneath the clouds.

Source: wiktionary

Grendel to His Mother [by Kirsten Dabrowski] Oh momma, momma, I'm just not a winner, / 'Cause I got roughed up on my way to get dinner. / I shrithed to the Heorot to get human yummies / To tickle our palates and fill up our tummies.

Source: wiktionary

While the winged creature coiled himself up, / the friend and lord of men stood unflinching / by his shield; Beowulf waited ready armed. / Then, fiery and twisted, the dragon swiftly / shrithed towards its fate.

Source: wiktionary

But the cruel monster constantly terrified / young and old, the dark death-shadow / lurked in ambush; he prowled the misty moors / at the dead of night; men do not know / where such hell-whisperers shrithe in their wanderings.

Source: wiktionary