Glassback: strike it when it beaches.

What it is

A black whale swimming in the lava seas of volcanic worlds, with a molten belly. It hunts whoever stands on the shore. It is based on lava, which cools into volcanic glass (obsidian) when it cools fast.

Where and when it comes

• On volcanic worlds only, in the lava seas.
• It comes from 25 to 45 metres away from someone standing on the shore of a lava sea.
• After one is slain, another cannot come for about 30 minutes. The Codex hint is "Something vast moving under the lava".

How it works

1. Breaching. It leaps from the lava, throwing molten rock that burns anyone near. Its crash comes down on whoever is on the shore.
2. Beaching. On the rock it lies beached for a few seconds. Its skin cools to glass, and the glass breaks: this is the moment to strike.
3. Basking. On a sunny day it basks at the surface. Its glassy back gathers the sun into a beam on you: first a glare, then a burn. Get rock between you and it.

While it basks, little gets through its hide.

Stats

Thing	Value
Health	1100
Length	About 9 metres
Splash of molten rock	16 damage in a 7 m circle
Crash	32 damage in a 5 m circle when it lands
Sun beam	11 damage, after about 1.6 seconds of glare, 40 m reach
Signature: Magma Spit	Three marks, 2.6 m across, 13 damage, about every 10 seconds

Tips

• Do not stand right at the shore. Its breach and crash reach the rock by the lava.
• Strike it while it is beached. The blow counts for more, as its skin is glass.
• When you see the glare, get behind rock at once.

What it drops

Drop	Amount
Ash-glass	5 to 8
Ruby	2 to 3
Gold pieces	4 to 8
Glass	10 to 17
Trophy	Glassback Scale

← Back to the wiki · Last updated 25 October 2026. Mantlenaut is in alpha, so things change.