A Monster Substitution Thought Experiment

Those of you who have read my blog for a while may have noticed that, when doing thought experiments, I like to limit the parameters (sometimes severely). For example, when I posted about finding future/sci fi monsters in D&D I limited myself to LL, Holmes and B/X. This resulted in some thoughts I knew wouldn't have occurred to me had I included the FF, as many commentators urged me to do.

When I was in elementary school, my school district would occasionally have in their budget the ability to bring in an artist in residence to do various projects with each grade level. The one that I remember best (because she had the most impact on me as a person) was a poet. One of the major life lessons I learned from her was that parameters and limitations can actually result in better work and more creativity. My free form poetry sucked, but my couplets and haiku sang. Thus, whenever I do thought experiments, the first thing I do is set limitations and parameters, because it almost always produces better work from yours truly.

I mention this, because there is really no reason for this particular thought experiment, other than it is a parameter that I think is really interesting and cool.  The other day, James over at Grognardia reminded all of us about the 3e SRD, especially all of the monsters listed therein. The post also reminded me that three of my favorite monsters from Homles and Cook are Not in the SRD:

• Caecilia (can anyone say baby purple worms?)
• Carrion Crawler (great for scaring the pants off of players)
• Displacer Beast (one of those monsters that inspires entire adventures)

I am sure that there are many who will gladly point out that, if push comes to shove, all I have to do is rename these wonderful beasts much like Dan Proctor did for LL (Gray Worm, Carcass Scavenger and Phase Tiger for those interested). But what if that wasn't possible? What if I had to use only those monsters in the SRD? What monsters would I use in their place? As I said, a useless (but fun) thought experiment:

• Frost Worm for Caecilia — I would have to reduce the number of HD (from 14 to 6) but I prefer the cold-based powers of the Frost Worm because it makes the creature more than merely a smaller version of the purple worm.
• Chuula for the Carrion Crawler — Again, there needs to be a reduction in HD (11 to 3+1); however, the basic concept of the two is very similar — a worm/insect-like creature with paralyzing tentacles. The difference is that the Chuula has a pair of claws that bring in its victim and can do some actual damage as opposed to just paralysis. Thus, it can put even more fear into players.
• Destrachan for the Displacer Beast — There is less of an HD discrepancy here (8 to 6) but more of a difference between the two concepts — phase displacement vs. sonic powers. If one takes into consideration the enmity with the blink dog, however, the sonic powers make more sense. Why would the blink dog ever develop the ability to blink in order to combat phase displacement (other than they seem to be related/have the same origin)? Blinking in and out in order to avoid sonic attacks, however, does make sense.

What are some of your favorite classic D&D monsters that don't show up in the SRD? What SRD monster would you be willing to substitute for them?