Complex sentence: With this, he heads on a quest to reclaim the Kingdom of Bretwalde, though, to avoid situations arising, he must not tell his comrades that he is not the real Serdic.
Split into simpler sentences: With this, Serdic heads on a quest to reclaim the Kingdom of Bretwalde. In order to avoid awkward situations arising, he must not tell his comrades that he is not the real Serdic.