Complex sentence: He bio-emerged near where Takato and Henry's field trip was camping, originally small under he drained enough of a nearby city's electrical power to increase his size while putting an owl under his spell to serve as his emissary.
Split into simpler sentences: He bio-emerged near where Takato and Henry's field trip was camping. Sinduramon was originally small in size until he drained and consumed enough of a nearby city's electrical power to increase his size, while also putting an owl under his spell to serve as his emissary.