The Deep Wyrm is a wyrm boss. At the lowest Threat it has 1296 health, hits for 30 and carries 6 armor; the uber version you meet in the Mortal Arena has ×1.6 the health and ×1.75 the damage. You need Deep Wyrm's Heart to call it out.

Every kill rolls its list 5 times. 0 Uniques sit on it: no ordinary ones splitting 0.0% of it between them, and no Exceptional ones splitting the last 0.0%.

It opens every fight with Tidebreath, then fights with Wing Buffet, Undertow, The Flood and Pressure Strike. The cast bar under its health names each big move as it winds up, so a party can call them out to each other. At 70% health it changes phase with Submerge into The Flood. After each big set piece it stops for a breath: that is the opening to punish. At 15% it makes its Last Stand with Tidal Doom, one named, fully telegraphed finisher, and no burst of damage skips it. The uber version in the Mortal Arena fights in three phases (Tide, Undertow and The Drowned Court), grows between them, and adds Riptide and Maelstrom. Its weak spot: Lure the Geysers. Stand by a Tide Stone when the water marks you: the geyser cracks the stone.

It calls in Frost Whelp.