Digimon: Digital Monsters - Season 2 - Eps 24: If I had a Tail Hammer
Ken finds a woman in his room who knows his past. While helping in the restoration, Davis, Kari and T.K. find that their Digimon can't Digivolve naturally despite the Control Spires being deactivated. Cody is attacked by Thundermon, leading to Armadillomon to Digivolve into Ankylomon. Thundermon is killed by Ken and Stingmon, leading the DigiDestined to become wary of him.
About Digimon: Digital Monsters

Title: Digimon: Digital Monsters
First Air Date: 1999-03-07
Last Air Date: 2001-03-25
Status: Ended
Rating: 8.1/10 (from 845 votes)
Language: JA
Seasons: 2
Total Episodes: 104
Network: Fuji TV
Genres: Animation, Action & Adventure, Sci-Fi & Fantasy, Kids
Production Companies: Toei Animation, Toei Company
Synopsis
While at summer camp, seven kids are transported to a strange digital world. In this new world they make friends with creatures that call themselves Digimon who were born to defend their world from various evil forces.
Cast

Reiko Kiuchi
Daisuke Motomiya (voice)

Megumi Urawa
Iori Hida / Armadimon (voice)

Rio Natsuki
Miyako Inoue (voice)

Hiroaki Hirata
Takeru Takaishi (voice)

Romi Park
Ken Ichijouji / Digimon Kaiser (voice)

Junko Noda
V-mon (voice)

Kae Araki
Hikari Yagami (voice)

Koichi Tochika
Hawkmon (voice)

Miwa Matsumoto
Patamon (voice)

Naozumi Takahashi
Wormmon (voice)