Cinder Wyrm is a dragon boss. At the lowest Threat it has 900 health, hits for 21 and carries 2 armor; the uber version you meet in the Mortal Arena has ×1.6 the health and ×1.75 the damage. You need Cinderwyrm Scale to call it out.

It waits at the end of Cinder Forge, in place of Imp Overlord, and belongs to Adventure Mode.

Every kill rolls its list 5 times. 8 Uniques sit on it: four ordinary ones splitting 90.0% of it between them, and four Exceptional ones splitting the last 10.0%, which puts any one of those at about 1 in 40 of what it gives up. The Exceptional ones are The Pyre King's Edge, Heart of the Furnace, The Ember Ledger and The Glassblower's Breath.

It opens every fight with Ember Breath, then fights with Furnace Sweep and Crucible Pounce. 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 55% health it changes phase: Furnace Unbound. After each big set piece it stops for a breath: that is the opening to punish. At 15% it makes its Last Stand with Inferno, one named, fully telegraphed finisher, and no burst of damage skips it. The uber version in the Mortal Arena fights in three phases (Ember, Inferno Rising and Forge Eternal), grows between them, and adds Magma Rain and Crucible Ring. Its weak spot: Choke the Breath. Hit the Wyrm while its maw glows — enough hits and the fire backfires.

It calls in Cinder Whelp.