B.O.S.S. (Battery Operated Super Simulator) is a machine within Bug Fables: The Everlasting Sapling that allows Team Snakemouth to fight previously defeated bosses. It is unlocked by presenting the Explorer's Permit to H.B., which has crystals in it capable of recording fight data.
Using B.O.S.S can be used to gain two unique medals, missed boss bestiary entries (via Spy) and Hard Mode achievements, but cannot be used to gain missed Hard Mode rewards, which are bought from the caravan.
When using B.O.S.S, Team Snakemouth has the option to select a Single Battle, where they select a boss or mini-boss to fight them individually, or Boss Rush mode, where there are two further options; Mini-Bosses fights all mini-bosses in a row, and Boss Rush fights all bosses in a row. Boss Rush does not include bosses/mini-bosses that have not been fought by the party yet and will skip over them to the next previously encountered one.
In either Boss Rush mode, Team Snakemouth may choose to regain all of their HP and TP between fights, up to 3 times per Boss Rush.
Defeating the third boss in either Boss Rush mode will award the Spy Specs medal, defeating the sixth will award the Detector medal, and completing the seventh fight in either will unlock the EX mode, which features mini-bosses and bosses with higher health than Hard Mode ones. Completing EX Mode Single Battles or EX Boss Rush will reward more berries for completion.
Items consumed during any mode will be given back at the end of the battle. The team is fully healed before beginning; they are also fully healed when it is completed.
After unlocking every mini-boss and boss, beating either Boss Rush will award a unique wall trophy that is placed in the purchasable Flower Key House in the Ant Kingdom City Plaza. The full mini-boss Boss Rush streak trophy is blue, while the full boss Boss Rush streak trophy is gold, both trophies feature the face of B.O.S.S.
Boss Rush Order
Both Boss Rush modes have a set order for fighting. The following is the list in which they are fought, in order:
- Acolyte Aria
- Dune Scorpion
- Monsieur Scarlet
- Kali and Kabbu
- Cenn and Pisci
- General Ultimax
- Zasp and Mothiva
- Venus' Guardian
- Heavy Drone B-33
- The Watcher
- The Beast
- ULTIMAX Tank
- Mother Chomper
- Seedling King
- Tidal Wyrm
- Peacock Spider
- False Monarch
- Wasp King
- The Everlasting King
- Acolyte Aria is fought with a full team, and she doesn't start the battle with a vine.
- The first fight with Zasp and Mothiva is only recorded in B.O.S.S. until the the team fights them a second time at the Colosseum. After this, the first fight is discarded, and only the second fight with Zasp and Mothiva is recorded.
- However, in the game files there is a leftover data for several Zasp and Mothiva options; the first one is unmarked, while the other two are labeled "Zasp and Mothiva #2" and "Zasp and Mothiva #3". This suggests that each fight with Zasp and Mothiva would've been recorded separately, and also confirms that Zasp and Mothiva would've had three fights over the course of the game.
- Neither Cross and Poi nor Primal Weevil are fought in the mini-boss rush, while Team Maki is not fought in the boss rush either.
- These mini-bosses are instead able to be re-fought in the Colosseum in the Termite Kingdom, while Team Maki can be refought by talking to Maki again.
- However, in the game files there is a leftover data for unused "Cross and Poi" and "Team Maki" options, suggesting that they were supposed to be fightable in the B.O.S.S. The reason behind their removal is most likely because they are already rematchable, so it would be redundant to make them refightable in B.O.S.S. as well.
- Kali and Kabbu are fought with a full team. This is the only instance where Kabbu is able to spy Kali and himself, displaying unique dialogue.
- The Beast does not have the phase where it instantly defeats Vi and Leif.
- Leif is not temporarily paralyzed at the beginning of the Zommoth fight.