Attack to Subdue

I brought up attacks to subdue creatures in my previous post. I plan on generalizing the rules to subdue dragons to apply to many intelligent creatures and some enchanted beasts, not just dragons. This seems reasonable, given the brief reference to subduing creatures in Men & Magic:

Capture of Non-Player Monsters: Morale dice can cause a man or intelligent monster to attempt to surrender or become subdued. When this happens an offer of service can be made (assuming that communication is possible) as outlined above. Subdued monsters will obey for a time without need to check their reactions, and such monsters are salable (see Volume II).

It's a little odd that the passage begins by suggesting that subduing a creature is a function of morale, but then directs you to the rules for subduing dragons. Also, this passage suggests that many monsters can be subdued, but only dragons can be subdued in Volume II. It's my instinct expand the subduing rules to other creatures, but still keep it limited. I'd reconcile the above contradiction by specifying two groups:

• humanoids, and other men and intelligent monsters who tend to fight in organized groups, are subdued when their morale indicates surrender.
• fantastic beasts, such as dragons but also others of at least animal intelligence, don't become subdued by mere morale failure, but must be explicitly attacked to subdue.

The process for subduing dragons not only includes percentile rolls, which I'm trying to avoid, but is also too distinct to be copied legally. I think I'd suggest this as a replacement: if a group attempts to subdue a fantastic beast, roll a d6 after every successful attack; a result greater than the creature's hit dice means that the creature is subdued. Add a bonus to the die roll equal to 1/6th the total of the damage done. If, at any point, anyone in the party does real (killing) damage, all subduing damage disappears and the party can no longer subdue the creature.

Edit: per Zornhau's comment, I should make it clear that "total" means "cumulative total". If you do total cumulative damage equal to maximum possible hit points, success is automatic. This does mean that you sometimes need to do more damage than the creature's hit points, if it did not have the maximum possible (6 hp per hit die.)