Sora acheives this digivolution after joining tais group and collecting data.This digimon is created by Phoenixmon,Garudamon,Birdramon,etc. go through god-digivolution or war-digivolution. Sora first does this when chasing apocalymon and wargulfmon.

Tai:"so their actually was something in for sora for joining me.Here I thought I'd be the only Fan Fiction/DigiDiety." Sora:"I'll have to thank Tai someday after this war of digidestined passes.I'm proud of you Biyomon (Adventure)". Two quotes from Fan fiction/Adventure 3, From the first time Hououmon/Phoenixmon digivolved.