From publisher blurb:
Bigger is not Better!
Too often in high-level Pathfinder Roleplaying Game play, your opponents are either high-level NPCs or towering titans of imposing size and strength. There’s nothing wrong with a colossal killing machine, but when you want creatures for your campaign that pack a powerful punch in a size small enough to walk right in the back door, you need Malevolent Medium Monsters! These are not outsiders with a million spell-like abilities, nor complicated classed characters, but honest-to-goodness monsters from CR 11 to 18 ready to terrorize your unsuspecting heroes as they tear them apart! You’ll find the paralytic alabaster beetle, the malformed composite homunculus dragon, the blood-soaked ersatz, the sinister and heretical faithslain, the grotesque misbirthed, and an entire new category of fiendfused monstrous humanoids that drink deeply from the wells of fiendish corruption to achieve an awful apotheosis! Each new creature is designed with full-page portraits, dynamic abilities, and detailed ecology, tactics, and advice on using it in the campaign, whether your heroes are facing invading demon hordes, exploring a wounded wasteland where chaos reigns, or expunging the tainted lineage of an ancient evil!