Excellent guide. The thoroughness and the amount of detail will surely help anyone who would like to try this deck in Underdog mode or even improve their game, if they are already using it.
Unfortunately, I think the team is aware that Mutations are a touch too strong in this mode and they will update the banned cards list to nerf this archetype somewhat:
Another minor thing if you decide to keep posting articles going forward. There are a few image sourcing rules that we're asking every author to follow. I created a post with examples specific for GU, to make this as easy as possible for everyone: https://peakd.com/hive-173286/@agrante/image-sourcing-for-gods-unchained-posts
If there is any other GU topic that would be fun for you to write about, don't be shy! Cheers!