The Ultimate Phase

is the thirty-seventh episode of Kamen Rider Build. It features the debut of the Great Dragon Evolbottle, Great Cross-Z Dragon, and Great Cross-Z. This episode also debuts Evol's Black Hole Form.
==Synopsis==
Had their operation succeeded, Evolto would have disappeared alongside Build. However, Evolto avoided death by possessing Sento’s body instead! But something else has happened. Because Evolto’s genetic signature was removed from Ryuga’s body after he possessed Sento, he can no longer transform into Cross-Z. Even so, Evolto was still strong enough to take over Sento’s body. In a state where he can no longer transform into Cross-Z, is there a chance that they can still defeat him?
==Plot==
to be added
==Cast==
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===Suit Actors===
*Kamen Rider Cross-Z: 
*Kamen Rider Grease: 
*Kamen Rider Rogue: 
*Kamen Rider Evol: 
*Engine Bro's: 
*Remocon Bro's, Hell Bro's: 
==Forms and Collectibles Used==
===Fullbottles===
*Bottle used:
**Cross-Z
***Biotic: Dragon Magma
***Abiotic: N/A
***Other: Cross-Z Magma Knuckle
**Grease
***Biotic: Kuwagata (in Twin Breaker), Fukurou (in Twin Breaker)
***Abiotic: Castle (in Sclash Driver)
**Rogue
***Biotic: Crocodile Crack
***Abiotic: N/A
*Form used:
**Cross-Z
***Cross-Z Magma
===Sclashjellies===
*Jelly used:
**Grease
***Robot
===Evolbottles===
*Bottle used:
**Cross-Z
***Biotic: Great Dragon
***Other: Great Cross-Z Dragon
**Evol
***Biotic: Cobra, Rabbit
***Abiotic: Rider
***Other: Evol Trigger
*Form used:
**Cross-Z
***Great Cross-Z
**Evol
***Rabbit Form (Phase 3), Cobra Form (Phase 1), Black Hole Form (Phase 4: Perfection)
===Gears===
*Gear used:
**Engine Bro's
***Gear Engine
**Remocon Bro's
***Gear Remocon
**Hell Bro's
***Gear Engine, Gear Remocon
==Errors==
*Right after Kamen Rider Evol slap on Ryuga's face, the suit actor of Evol, Kazuya Okada, can be seen not wearing the mask.
==Notes==
*As part of Super Hero Time, this episode aired alongside episode 16, .
*Viewership: 2.3%
*Formula of the title: \underset{\rho :prime}{\arg\min}[\rho \not\in \{regular\}]=37 ( )
*Evolbottles Obtained: Great Dragon
*Closing Screen Evolbottles:
**Kamen Rider: Cross-Z
**Evolbottles: Dragon, Great Dragon
*Count at episode end
**Bottles in Build's possession: FullFull RabbitTank
**Bottles in Cross-Z's possession:
***Biotic: Dragon Magma
***Abiotic: N/A
***Other: Cross-Z Dragon, Cross-Z Magma Knuckle
**Bottles in Grease's possession:
***Biotic: Kuwagata, Fukurou
***Abiotic: Castle
**Bottles in Rogue's possession: Bat, Crocodile Crack
**Bottles in Evol's possession: Cobra
**Jellies in Grease's possession: Robot
**Gears in Engine Bro's's possession: Gear Engine
**Gears in Remocon Bro's's possession: Gear Remocon
**Evolbottles in Cross-Z's possession:
***Biotic: Great Dragon
***Other: Great Cross-Z Dragon
**Evolbottles in Evol's possession:
***Biotic: Cobra, Rabbit
***Abiotic: Rider
**Bottles at nascita:
***Biotic: Rabbit, Taka, Panda, Dragon, Kaizoku
***Abiotic: Tank, Gatling, Rocket, Lock, Densya
***Other: RabbitTank Sparkling
**Bottles in Pandora Box:
***Biotic: Gorilla, Ninjya, Harinezumi, Lion, Octopus, Phoenix, Wolf, Unicorn, Rose, Turtle, Kabutomushi, Kuma, Dog, Santa Claus, Spider, Tora, Kujira, Shika, Kirin, Penguin, Obake, Same, Bat, Hachi, Sai
***Abiotic: Diamond, Comic, Syoubousya, Soujiki, Light, Robot, Smapho, Keshigomu, Helicopter, Watch, Camera, Televi, Mic, Cake, Reizoko, UFO, Jet, Pyramid, Senpuki, Sukebo, Magnet, Bike, Engine, Sensuikan, Dryer
*This is the first episode since it's debut that Sento does not assume Build RabbitRabbit Form. 
**It is also the first episode where Sento doesn't transform into Build due to him being possessed by Evolto.
***This is the first series since episode 47 of Kamen Rider W where the main Rider doesn't transform in an episode.
==External links==
*TV Asahi's official episode guide for 究極のフェーズ
*Toei TV's official episode guide for 究極のフェーズ
==References==
Category:New Form Episode