Rainbow Palace is the secret/final area in the game Bomberman 64. The player must collect 100 Gold Cards and then defeat Altair to unlock this level. It is a palace filled with stone pillars and walkways with a shrine at its center and enemies called the Card Servants and Eleki. Above the shrine is a small room with a green roof where Sirius awaits the final confrontation.
Beyond the CloudsWhite Bomberman just made it into the skies but finds himself just outside the Rainbow Place. White Bomberman must find a way to get inside by pressing switches to open the doors. However, the switches are out of reach and White Bomberman must work his way around using the bomb bridge method. This can be done by gathering all of the extra bombs around and getting the remote control bomb. White Bomberman must also be careful of the Card Servants around that may hinder his progress. After pressing the switch, White Bomberman can now enter the castle.
Vs. SpellmakerBefore he can go any further, White Bomberman finds himself fighting Sirius' strongest servant: Spellmaker. Spellmaker is a very unique boss that possess numerous of attacks including throwing exploding cards, making a flaming dragon appear, and even cause a star shower. Spellmaker can be a very difficult boss since White Bomberman will not be using any remote control bombs during this boss fight. Hitting Spellmaker directly is useless as well so White Bomberman must aim for his shadow. After many hits, Spellmaker goes down leaving White Bomberman to go further into the castle.
Doom CastleWhite Bomberman finally made if further into the castle and is now ready to confront Sirius. However, the main castle doors are locked meaning White Bomberman must find the switches to open them. However, all of the switches are located a little higher up than usual meaning White Bomberman must restort to using the bomb bridge method once more. After pressing the switches, White Bomberman can finally face Sirius.
The Final Battle!As soon White Bomberman enters, Sirius activates the Omni Cube transforming the battlefield into a space-like place (similar to the intro). For this first phase, White Bomberman must damage Sirius. However, Sirius tends to fly around and launch lasers attempting to burn White Bomberman. White Bomberman must wait until Sirius is on the ground to damage him. After enough hits, Sirius decides to end it and powers up his strongest blast attack. However, Regulus suddenly appears and destroys the Omni Cube turning the battlefield back to normal. Sirius is displeased by this and Regulus decides to team up with White Bomberman. For the second phase, Regulus will be an ally and will attack Sirius. Regulus has about 5 hearts before he goes down. If Regulus is damaged, White Bomberman can pick up a heart for himself to keep in the battle. Sirius is also capable of using the blaster attack which has great range. The best way to avoid this is to stay far back. After taking a certain amount of hits, Sirius blows up to nothing.
After Sirius is defeated, the Rainbow Palace falls onto the Black Fortress destroying the both of them and Regulus flies White Bomberman out of the destruction back to Planet Bomber. Regulus comments on White Bomberman's fighting strength but says the next time they meet, they will fight. Regulus flies off and White Bomberman celebrates along with the rest of his people.