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Sonic News Network
Sonic News Network

The Egg Inferno,[1][2] also known as the Hot Mobile[3] (ホットモービル[4] Hottomōbiru?), is a vehicle that appears in the Sonic the Hedgehog series. It is a submarine-based Egg Mobile that can go under magma.



The Egg Inferno is a sphere-shaped capsule with a black bottom, thick gray armor on the upper half, a transparent window on the front, a spiked rim encircling the top of the vehicle, and extra long spikes protruding diagonally from the sides of a low-set cannon on top of the Egg Inferno.

Powers and traits

The Egg Inferno is resistant to incredibly high temperatures, being able to submerge itself in magma without taking any kind of damage. It is also capable of flight, is equipped with missiles, and can fire iron balls from its top cannon.


Sonic the Hedgehog 3 & Knuckles

In Sonic & Knuckles and the lock-on game Sonic the Hedgehog 3 & Knuckles, the Egg Inferno was used by Dr. Robotnik to ambush Sonic and Tails while the duo were making their way through the Lava Reef Zone by firing the Egg Inferno's missiles at them. However, the two heroes were able to dodge the Egg Inferno's missiles, though they were eventually forced down to a pool of magma at the foot of a magma fall. Finding Sonic and Tails with only slivers of solid rock to stand on above the magma pool, Robotnik engaged them with the Egg Inferno. However, by turning the Egg Inferno's iron ball projectiles against the Egg Inferno, Sonic and Tails were able to damage the Egg Inferno enough to make it sink into the magma, which soon hardened. Robotnik survived this setback though.


The Egg Inferno is the boss of Lava Reef Zone Act 2 in Sonic & Knuckles and Sonic the Hedgehog 3 & Knuckles. It is the overall ninth boss in Sonic's story in Sonic & Knuckles and the twenty-second boss in Sonic and Tails' stories of Sonic the Hedgehog 3 & Knuckles.

In Sonic & Knuckles, the Egg Inferno is fought by Sonic. In Sonic the Hedgehog 3 & Knuckles, it can also be fought by Tails. In addition, if both Level Select and Debug Mode are enabled in Sonic the Hedgehog 3 & Knuckles, it can also be fought by Knuckles.

Boss guide

The battle is split into two phases. In the first phase, the player must simply keep up with the auto-scrolling section while Robotnik destroys the platforms with missiles, taking care to avoid falling into the bottomless pits. The player must then jump across platforms that crumble shortly after the player steps on them. The auto-scrolling section ends when the player reaches a lava waterfall with platforms that slowly fall down along with the lava. The player can then fall down to fixed platforms containing a Lightning Shield and some Rings while another platform has a Flame Shield. The player can drop down into the lower-left part of the lava waterfall thus commencing the second phase of the boss fight, when a falling platform on the left-most column finally touches the lava floor.

The objective of the second phase of the fight is simply to dodge obstacles and not touch the Heat Mobile. The Heat Mobile will tilt the lava floor diagonally towards it, sliding the platforms along it in attempt to drag the player into touching the boss. If the player does not have a Flame Shield, they must land on the platforms and not touch the lava. Dr. Robotnik will shoot iron balls which will land on the lava floor so the player must be aware in order to dodge them though they will also slide down along with the platforms and will damage the Egg Inferno upon contact. After shooting three iron boss, the lava floor will be flattened out temporarily, preventing the platforms from sliding down the slopes. The Heat Mobile will sink and then appear on the other side and resume its attack pattern. After receiving fourteen hits from the iron balls, the Egg Inferno will be destroyed, leaving a single platform at the middle of the stage. The player can then proceed to hit the Capsule which hovers across the stage while slowly dropping down to clear the stage while minding the lava is still harmful.


  • The entire fight against the Egg Inferno is designated as Lava Reef Zone Act 3 in Level Select. This also allows the player to fight this boss as Knuckles if Debug Mode is also enabled with Eggrobo in the cockpit.
  • Because this boss cannot be damaged by the player, this can be considered the longest fight in the game when attempting a speed run.
  • The Egg Inferno is the only main boss in the game that cannot be hurt by Sonic or Tails by any means; not even Super Sonic, Hyper Sonic, or Super Tails can damage it.
  • In the 2022 remaster of Sonic the Hedgehog 3 & Knuckles featured in Sonic Origins, the arena of the second phase of the fight has been notably widened due to the widescreen feature. This allows up to three platforms to be on-screen at a time as opposed to two in the original versions of Sonic & Knuckles and Sonic the Hedgehog 3 & Knuckles. Furthermore, after the Egg Inferno is defeated, two platforms will be present in the middle instead of one, reducing the risk of landing on the lava.


Name Artist(s) Version Length Music Track
"Boss 2" Sega Sonic & Knuckles/Sonic the Hedgehog 3 & Knuckles 1:14
Sonic & Knuckles Collection "FM Synthesizer" 1:09
"General MIDI" 1:05




  1. Sonic Team (23 June 2022). Sonic Origins. Sega. Area/Level: Boss Rush (Sonic the Hedgehog 3 & Knuckles). "Boss Rush 10/11 - vs. Egg Hanger"
  2. Flynn, Ian; Sega (8 December 2021). Sonic the Hedgehog Encyclo-speed-ia. Dark Horse Books. p. 58. ISBN 978-1506719276. "Bosses - Egg Inferno"
  3. Flynn, Ian; Sega (8 December 2021). Sonic the Hedgehog Encyclo-speed-ia. Dark Horse Books. p. 55. ISBN 978-1506719276. "Bosses: Act 2 - Hot Mobile. Dr. Eggman's pod controls the magma flow and destroys your footholds while launching mines. Find the Flame Shield at the start of the magma falls to mock his efforts."
  4. (in Japanese) ソニックメガコレクション最強攻略ガイド. Shogakukan. 1 March 2003. p. 175. ISBN 978-4091060907.

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