What I really want is a system for both creating unique monsters and also a built in system for fighting large special creatures. Any reference relating to a hero slaying a great monster is full of special moves and tactics, sometimes the hero exploits the monsters single weakness in a clever way (Brand vs Smaug) , sometimes the hero stands and lets the beast make its attack- facing certain doom with grim determination - but then at the last moment the hero thrusts his blade through the roof of the creatures' mouth and into its' brain (Liam vs Snake).
The stories are full of particular reference to specific body parts that the hero targets. I think that is important. A regular D&D opponent - an Orc- has a fixed hp amount total, a reasonable figure which represents the number of times he can withstand a sword blow or a magic missle before being taken out of action, killed, etc. This is all well and good for an Orc, but for a Dragon I think it falls apart, that a fixed number should say a Dragon can suffer x amount of spear thrusts is really weak in my opinion.
I think that there are two primary ways a great monster can be killed; in pieces or all at once. I also suppose a beast could be slain in pieces and then all at once. That is to say I believe a hero should be able to target specific parts of the monster, which individually have an hp amount - say that The Great Black Dragon has two front claws, each with 50hp, once a claw is reduced to 0hp it is out of action and unable to attack or be of any further use until healed. This way heroes have choices during fights with Legendary Creatures- the fighter can try to fend off the claws while the archer stays back and tries to put that critical instant-kill arrow into the beasts left eye.
I have alot more to say about this. I realize most of what I say above seems like a weird jumble of wish list crap, but I have actually been working on how all this will work and I think it will work better in practice than it sounds here as I try to explain it. My main problem is that I am developing this at the same time as Im trying to come up with my own BX inspired ruleset (which I will post on here as it comes to me). I think for the meantime as I post the rules for Legendary Creatures I will keep the rules non-system specific.
I think for the next Legendary Creatures update I will use a case study featuring everyone's favorite barbarian squaring off against The God Lizard. Cheers.