It’s exclusive game content or backer builds, obviously! But apart from that:
A quick way to get a look at new content. All tomes and locations unlocked by default, reduced in-game prices, and if you fail to recruit a minion, you can undo your last turn.
A retune for roguelike replayability. More intense invasions, and a bad ending scene if you lose. Designed to be shorter and much tougher.
Just go hog wild: insta-recruit minions, give your self more mana, complete minion transformations immediately, etc.
I hear people like these? I’m probably not going to turn voice on for you though, no offense. 🙂