OK, this will probably be long winded so please bear with me. I’ll be quoting multiple threads as well.
I assume you meant to say "in previous editions, the HD and level of specifically PC-classed NPCs were the same", since the statement doesn't hold true when discussing monsters.
No that is not what I mean. HD has been used from the beginning to determine a monster’s ability to hit a target just like level for a PC. The higher the HD the better the chance to hit. Check the following sources:
1. Basic D&D from 1979 rule book page 19
2. Basic D&D from 1981 rule book page B27
3. Expert D&D from 1981 rule book page X26
4. AD&D DMG page 75
5. 2e D&D DMG page 53
Under 3e, the Base Attack Bonus (BAB) was determined by the Type of creature, number of HD, and a PC class reference for progression; i.e. an 8 HD giant would use a 6 level cleric BAB. Reference Core Rule Book III Monster Manual page 13.
I don’t know about 4e as I didn’t play that rule set. 5e uses CR to determine the proficiency bonus used for attacks, not HD.
In 1e and before, a monster's or npc's character level/HD had very little to do with its "monster level".
I would disagree with you on this point. First, I never actually said monsters have a level, Second, as stated above, HD was used to determine the “to hit” chance. If you increase the HD the better the chance to hit the target. I remember playing basic games and saying “Wow, we just beat a 5HD monster!” Sounds similar to saying “Wow, he is a 7th level fighter.” They weren’t direct equivalents by any means. In 2e, a 1+1 HD monster had a THAC0 of 19. PC classes reached THAC0 19 at level 2 for the “Warrior” group, level 3 for the “Rogue” group and level 4 for the “Wizard” group. The “Priest” group skipped THAC0 19 and jumped from 20 to 18 at level 4. For any reading this that are not familiar with 2e, like classes were placed in groups, e.g. Fighters, paladins, and rangers were in the “warrior” group. Saved space in the rule books when creating tables and matrices.
I'd be curious to hear what your priorities in generating a playable encounter are and how your system succeeds at that.
I’ll be very honest with you on this, I don’t have a set rule, formula, or system for building my encounters. I’ve been playing for so long that I have a “feel” for it. If during a gaming session the PCs seem to having their way with an encounter, I’ll bump it on the fly; add 2 more orcs to the tribe. If the encounter seems to be overpowering them, I’ll scale it back or have the enemy not use the proper tactics; the glory hungry orcs charged instead of staying back and using bows to decimate the party. I don’t allow what I have prepared or what is in a pre-generated module to shoehorn me into a corner; my gaming session, my prerogative. I want the players to have fun and be challenged. At the end of the session I want them to be excited about having accomplished something, and I don't mean just surviving, relieved, and wanting another session. I think of it as a roller coaster ride, you conquered your fear, it's over, but you really want to do it again.
It doesnt say mage(wizard)
it just says Mage
I understand that. I don’t want to get into semantics in this but at some point in time in the varied additions, Mage, Magic-User, Wizard, Sorcerer, Warlock, and a slew of other titles were synonymous for a single class originally known as a Magic-User. A 1st level fighter was also known as a “Veteran.” If I had never played the game before, I might not pick up on subtleties like this, but I've played for way to long not to notice them. To me, rules should not introduce ambiguity. Perhaps the new DMG will clear some of this up, I hope.
Sparrowhawc