The Boss Monster Strategy Guide is a digital PDF included with certain pledge levels on Kickstarter. The guide has information on every Boss, Room, and Spell card included with the Base Set.
The Strategy Guide was included along side a digital copy of the games Soundtrack.
Brotherwise Games has stated that they may release a physical copy of the Strategy Guide last, if there is demand for it.
Trivia[]
The guide is very likely a parody of Nintendo Power magazines from the late 80s to early 90s. Many things suggest this: the stripes on the magazine cover, the coloring and style of the table of contents, and the titles of the sections in the guide.