That depends on what game you want to play. Flee Mortals is a 5e product made for a d20 system, so if you're playing a game like D&D 5e, and want those monsters, then buy that.
The MCDM RPG Monster book will likely have many of the same monsters, but the mechanics of their new game will be very different. The new RPG is currently planning to use a 2d6 system, not a d20 system. So, the two books may look similar in terms of monster content, but they won't really be compatible with each others game systems.
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That depends on what game you want to play. Flee Mortals is a 5e product made for a d20 system, so if you're playing a game like D&D 5e, and want those monsters, then buy that. The MCDM RPG Monster book will likely have many of the same monsters, but the mechanics of their new game will be very different. The new RPG is currently planning to use a 2d6 system, not a d20 system. So, the two books may look similar in terms of monster content, but they won't really be compatible with each others game systems.
Engaged with this project 10+ times 🌟
Very helpful thanks!