Failed Monster Designs

Although I have written about bad monsters in RPGs, you can identify another type I have sometimes written about: the failed monster, whose basic idea is OK but whose mechanics are off. Either it's too weak or too strong relative to expectations, or just not a good join-up between concept and implementation.

Some examples, from AD&D first edition, with my writings about the first three:

• Ghosts are super-powered, with “zap” effects like aging and possession, but aren’t really true to the variety of their source material. It's a similar failure to golems. There should be lower-level hostile living statues (as in Basic D&D) and lower-level hostile hauntings.
• The gelatinous cube as a 4 HD bag of hit points just doesn’t, er, gel.
• Piercers can be much improved. 
• The carrion crawler with eight attacks is an overpowered paralysation machine. It hits plate and shield on a 14. Good luck!
• The slithering tracker is an undescribed, underdeveloped monster – really, more of an effect -- of consummate unfairness.It tracks you invisibly, paralyzes you in your sleep, and kills in six turns. There is no way to set watch for it unless you're willing to prod sleeping comrades every hour for a reaction.
• AD&D dragons are borderline failed. Certainly their implementation in 70’s-80’s D&D, with fixed HP and breath weapon damage, substitutes “special” for “scary,” and has been repudiated by every edition since and even some retro-clones.
• Harpies are mixed-up with sirens. There should be just normal shitbird harpies. Charm-harpies should be more powerful than they’re given credit for, with squads of charmed minions.
• The oddly specific horror story of the night hag is hard to use in actual adventuring. Like the Fiend Folio’s penanggalan and revenant, the hag’s description is focused on her threat to a lone civilian. It's assumed the party is supposed to barge in upon and rectify the haunting and draining by the hag, even though the victim by definition has to be exceedingly evil.

A common theme in these and other failures: indecision about combat encounters. There's a desire to make monsters about more than a line of stats, to make fighting them a matter of strategy and decisions as well as lining up and whaling on them. But these work better as rules than as haphazard monster effects. That way the strategy can generalize, and be inverted, working for both sides. Just some examples, some of which I've written on:

• Monsters can be scarier, and true to life, by coming into close combat where your weapons are less effective.
• Little monsters can, and must, climb you. You can also, and must also, climb big monsters.
• Flying monsters should be annoying as hell.
• Immunity/resistance to weapon effects. No flesh, can't slash. Nothing hard, can't bash. No vital points, can't pierce.
• Monsters with that one weakness. Puzzle monsters, in a word; murderous locks with murdering keys.