The Underpin Delve Guide (Demolition Dome)

The Underpin Delve Guide (Demolition Dome)

Written by Roguery - 13th March 2025

Demolition Dome is a unique delve containing only a single boss, The Underpin.

This delve is Patch 11.1's version of Zekvir’s Lair, still only having 2 difficulties ? and ??. The recommended item level for ? is 639 and will introduce the basic mechanics of the encounter.

The ?? has no recommended Item level and is exceptionally difficult; expect to wipe a lot as you learn the encounter.

Like other delves, Demolition Dome can be done either solo or as a group.

Demolition Dome Location

The Demolition Dome is located in the very north of the Undermine Zone.

Demolition Dome entry Location MapDemolition Dome entry Location
/way Undermine 52.16 9.24

The Underpin’s Mechanics

You may have already encountered The Underpin as he can randomly appear in any delve, at tier 8 or higher. If you have met him already you will have experience with some of his ? mechanics. We breakdown all of The Underpins Mechanics below, in both ? and ?? difficulty, and how best to deal with them. As The Underpin uses the same mechanics in both difficulties, we have only added the changes to ?? section, so if you are dealing with the ?? make sure you read both ? and the ?? section.

The Underpin’s “?” Difficulty Abilities

This is the easier version of the encounter. That being said it can still be a challenging encounter, although a bit easier than Zekvir was. He has a few abilities you will need to deal with:

  • Crush - The Underpin jumps in the air and targets a player with a slam, deals heavy physical damage and stuns for 4 seconds if caught.
  • Flamethrower - Targets the closest unit and after a short cast does a locked on frontal cone that deals heavy fire damage and leaves a damage over time.
  • Time Bomb Launcher - The Underpin launches several bombs in the air that land nearby , they have a ten second timer and they explode in a 15 yard area dealing heavy damage. These bombs can be kicked at the Cronies to deal damage to them.
  • Signal Cronies - The Underpin summons 3 Cronies around the edge of the platform, these deal constant ticking damage and cast Molten cannon which fires orbs at the player which deal moderate damage and knockback. Defeated cronies leave behind a fire patch on the ground.
  • Divert Energy to Shields - When the Underpin reaches 100 Energy he gains a shield, he then starts to cast recharge for 25 seconds which if successful heals him for 25%.

The Underpin’s “??” Difficulty Abilities

Unlike Zekvir, The Underpin does not gain any new abilities for the “??” difficulty, and instead modifies his “?” abilities making the encounter much more hectic, this paired with him having more damage and more health makes the “??” difficulty a much harder challenge. Below we have listed the changes to the abilities.

  • Time Bomb Launcher will now continually spawn circles around the boss for a duration after casting it, making it much more difficult to stay in melee.
  • Signal Cronies now summons 5 Cronies instead of 3.

The Underpin Strategy

Based on our experience with The Underpin, we recommend doing the following

  • Try to stay close to the boss so you can position the Flamethrower and Crush.
  • Use DPS cooldowns when he casts Divert Shield to quickly remove his shield and stop him from healing.
  • Slowly kite around the edge of the room to avoid the corpses of the Cronies.
  • Binding the Interact key makes interacting with the bombs a lot easier.
  • Kick bombs at the Cronies so you can focus damage on The Underpin.
  • If the Cronies spawn in the stands of the arena, just reset the encounter and try again (we assume this is a bug and not intended).

Recommended Brann Build

We recommend setting Brann as Damage. Then use the Goblomagnetic Bouncing Grenade or Mechasaur EZ-Build Kit combat curios, we then recommend using the LOOT RAID-R utility curio. This should give Brann a reasonable amount of damage which can be necessary to break The Underpins shield phase. We also recommend Brann to be around level 50 or higher as much lower you might struggle a little.

Demolition Dome Delve Rewards

Defeating The Underpin on either difficulty will reward the My New Nemesis achievement which rewards the Golden-Gob Propulsion Rig. You will also receive Brann’s Spare Hat, by handing in the quest Defeating the Underpin. The Underpin also seems to drop the utility curio Pacifist Rig.

By defeating The Underpin on ?? difficulty will reward you with the Breaking the Bank achievement and the Real Deal title. Defeating the Underpin in ?? difficulty solo rewards you with the Delver's Gob-Trotter Schematic: Gold, which is a transformation for the season 2 delve mount.

We hope this guide helped you better understand the Underpin encounter and earn some cool transmog and a nice gold version of your Season 2 Delve mount.

Other Guides see more