RabbitTank Hazard Form

" Hazard On! Rabbit! Tank! Super Best Match! Don Ten Kan! Don Ten Kan! Gata Gata Gotton! Zuttan Zutan! Gata Gata Gotton! Zuttan Zutan! Are you ready? Uncontrol Switch! Black Hazard! Yabei!" - The announcement for RabbitTank Hazard.

RabbitTank Hazard Form (ラビットタンクハザードフォーム Rabitto Tanku Hazādo Fōmu) is one of the forms in Kamen Rider Build. It is used by Sento Kiryuu. It is unlocked by notching the Rabbit and Tank Fullbottles with the Hazard Trigger's power. It is also Sento's turbocharged super form. 

The form first appeared when Sento had gained the Hazard Trigger from Soichi Isurugi. He wanted to test it out, while Ryuuga Banjou was fighting three Hazard Smash. When Sento transformed into this form, he is instantly lost his grip of control and went berserk in The Unstoppable Hazard. The suit is portrayed by Seiji Takaiwa with the voice of Atsuhiro Inukai.

FangJoker

"Fang! Joker! FangJoker!" - The transformation sound for FangJoker.

FangJoker (ファングジョーカー Fangu Jōkā) is one of the forms in the series Kamen Rider W. It is transformed to by the Fang Memory and the Joker Memory, used by Shoutarou Hidari and Philip, and the Double Driver. Unlike other Double forms, FangJoker uses Phillip's body for transformation.

He first appeared in The F Afterglow/Reclaim Your Partner, after Philip successfully uses it, but going berserk afterwards. After he got tired, they switched to their CycloneJoker form once more. The suit is portrayed by Seiji Takaiwa, with the voices of Masaki Suda and Renn Kiriyama.

Akaba

"Boss... thank you... for everything," - Akaba's last words, before handing Kazumi Sawatari his dog tag.

Akaba  (赤羽 Akaba) is one of the minor antagonists in Kamen Rider Build. He was born as Masaru Ooyama (大山勝 Ōyama Masaru, but after being experimented on and joining Kazumi Sawatari, he was given the name Akaba, thinking that Kazumi would actually refer him as so. Later in the series, Akaba becomes part of Sento's team, after Kazumi lost the proxy battle. He uses the Castle Fullbottle to transform into Castle Hard Smash. Later on in the series, he gets upgraded into Castle Hazard Smash. He is portrayed by Eishin.

Den-O Sword Form

"Sword Form!" - The announcement on transforming into Den-O's sword form.

Den-O Sword Form (電王 ソードフォーム Kamen Raidā Den-O Sōdo Fōmu) is one of the main form in Kamen Rider Den-O. Sword Form first appeared in Here I Come, first appeared after Momotaros entered Ryoutarou Nogami. He pressed the red button and transformed into Sword Form, and easily defeated Bat Imagin. The suit of Sword Form is played by Seiji Takaiwa, with the voice of Toshihiko Seki.