From the introduction:
Welcome to the Lusus Naturae II, a guide to freaks of nature, monsters and beasts. This guide is meant to be used with the Throwigames Simple Roleplaying System (TSRS). This second monster guide continues where the first guide left off – it contains more difficult monsters and beasts found within the TSRS world, ranging from PR13 to PR25. Additional guides detail further bizarre and unique foes.
As with all TSRS guides, the rules and statistics found within are only suggestions for the GM. The difficulty, number and rewards of each foe can be adjusted in any way needed. Each creature has been designed with the premise that the game world is an extremely harsh place and material rewards are few and far between.
This guide does not provide extensive descriptions of each and every monster. It is assumed that the GM has used or seen similar monsters in other game systems. Unique monsters to this system will be given as much detail as possible.