Due to enemy units' high defense, the metal units generally cannot be hit for more than 1 damage per hit. It is advisable to use units whose attacks hit multiple times for faster kill. Other methods including using specific leaders or units to increase damage in particular ways such as ignore defense effects to deal normal damage or to increase damage high enough to simply tread over their defense. Their HP is as follows:
God - 100 HP
Crystal - 300 HP
Metal units of other elements are also obtainable and will be listed below under Monsters.
Normal Attacks, Single Target and Multi Target BBs & SBBs all have only a single check for defence penetration, whereas every hit of a Random Target BB/SBB has an individual chance to penetrate defence, making units like Holy Arms Douglas, Inferno Princess Dia, and Void Pasha Ensa-Taya very useful when combined with a Ignore DEF leader or sphere.
One popular method uses two Heavenless Bushi Mifune (either one can be leader) with the SP option "50% boost to Atk" chosen. An optional leader includes Toki if you feel you require more damage. Both Mifune must be equipped with spheres to increase their damage as high as possible. This could be stat spheres such as Divine Wings, Sky Harbinger, Amenonuhoko and Nevana Crown, along with secondary spheres such as Skull General, Delusion Device, Ultima Weapon, Vorpal Chainblades, and others which raise attack as high as possible. Remember not to pair spheres which increase damage for several turns only with each other as they do not stack. Consider Elgifs which increase damage as well. With this, both Mifune can simply be set to use normal attacks to oneshot any Metal or Crystal God encountered, while the Toki leader (if taken) along with the friend unit can be set to guard.
As of March 21, 2018, all quests for the dungeon now require 0 energy.