Adamant bills this product as correcting two specific flaws in the monster creation guidelines given in the "DM's Toolbox" section of the 4e DMG: (1) DMG-bred monsters are overpowered at high levels, and (2) Monster Manual monsters don't follow the DMG guidelines. The key questions for evaluating the success of Adamant's Monster Maker are (1) whether you agree that those flaws really exist, and (2) whether Adamant does a better job than WotC at showing you how to create 4e monsters.
On the first score -- whether DMG-bred monsters are too powerful at high levels and whether Adamant's Monster Maker does a better job -- I don't actually agree with the premise. The introduction to Monster Maker practically equates "more exciting and faster-paced monsters" with "monsters that don't hit the PCs as often and get hit by the PCs more often." As a DM, I'm not convinced that's a good thing, especially at epic tier, where PCs can have abilities that begin "Once per day, when you die ..." But suppose that you do agree with Adamant that DMG-bred monsters are overpowered. If so, you'll find that building monsters with Monster Maker instead of the DM's Toolbox will yield monsters that generally have weaker defenses and lower attack roll modifiers than DMG-bred monsters.
But that's just about where the differences end. To test just how different Monster Maker monsters would be from DM's Toolbox monsters, I took three Monster Manual monsters -- the visejaw crocodile (level 4 soldier), azer raider (level 15 brute), and efreet pyresinger (level 25 controller) -- and tried to recreate their basic stats using the DM's Toolbox and Monster Maker. Except for the efreet's defenses and attack bonuses, the results from the DM's Toolbox were very similar to those from the Monster Maker, and also very similar to the actual finished monster in the Monster Manual. You can see detailed comparisons at http://d20.heardworld.com/?p=368 if you wish.
I also took two of the sample monsters presented in Monster Maker -- the rock ape and movie zombie -- and tried to recreate them myself using the Monster Maker itself and the DM's Toolbox in the DMG. I was surprised by the results: the Monster Maker and the DM's Toolbox gave very similar guidance, and the actual creature writeups in Monster Maker differed from the Monster Maker guidelines more than the DM's Toolbox guidelines differed from the Monster Maker guidelines! Admittedly, both creatures are heroic tier monsters, and the differences should be more evident at the paragon and epic tiers. Even so, with results like this (which, again, you can view in detail at http://d20.heardworld.com/?p=368), the charge of WotC "not following their own guidelines" rings hollow when echoing against Adamant's own departures from their alternate guidelines.
On the bright side, the artwork is reasonably good (though I don't know if it's unique to this product), and if nothing else, you do get three new monsters, one of which is a dragon statted out at multiple ages.
Overall, I found this product rather disappointing. Given that the Monster Maker and the DM's Toolbox produce very similar results, that Adamant's method requires more complex math (and directs you to round fractions up, different from the standard D&D practice of rounding down), and that big portions of the text just paraphrase what's in the DMG, I expect that I will keep using the DMG's guidelines instead of Adamant's.
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