Golems.

Those are pretty obvious problems and warrant multiple lives for the people who have a lot of feats. They will be skilled and they might want a crown. That means they have to face off against the world even if they get the crown. No matter how skilled they are, they will always be vastly outnumbered without being able to hide. 

Anyone with a crown can run but they can never hide. That doesn't mean there can't be any hidden problem. So he decided to be vigilant and very careful. Salvos is already a hidden danger. If the hell bringer is not enough to make him alert, then the problems that he can't anticipate will do the trick. There's also Salvini and the people banding together to make his life very difficult in this challenge. So he has a lot to look out for.