Monster Ability Scores

     D&D Next gives each monster type a full set of six ability scores, necessary because saving throws (in addition to other stat checks) are based on these scores. Monster ability scores are not generally used in old-school D&D, but are also not entirely antithetical - particularly in Holmes Basic. The very module from which the playtest scenario was derived, B2 Keep on the Borderlands, is the only TSR module to include a DX (dexterity) score in the stat block for each monster. This was because initiative in Holmes Basic went in order of dexterity. In the rulebook, Holmes simply suggested rolling the dexterity of each monster on the spot; In B2, Gygax sped this up for novice DMs by including the stat for each monster. Most of the monsters in B2 have the same DX score for each type, allowing extrapolation of Gygaxian typical DX scores for these monsters. Here's a breakdown of the DX scores for the Caves of  Chaos monsters in Holmes Basic vs D&D Next:

     Most monsters have from 1-3 points added from Holmes Basic to D&D Next, while a few remain exactly the same (Ogre, Minotaur) and a number of others have 6 or 7 points added (stirge, giant rat, wight, gelatinous cube, bugbear). Only a single monster, giant centipede, is 1 point slower in D&D Next. Dexterity inflation!

     Another section of Holmes that implies monster ability scores is the Charm Person spell, which allows new saves based on intelligence for all persons, including various humanoids. The INT scores for humanoids are not specified, but it could be inferred from the suggestion for dexterity that the referee should roll for these monsters. Furthermore, the table ends with "18 or higher", suggesting higher than human INT scores exist. This was furthered in the AD&D Monster Manual, which provided an Intelligence rating for each monster entry, which were correlated to character INT ranges in the introduction. The Monster Manual also has a few residual mentions of monster dexterity scores (e.g. the Brownie has an 18 dexterity). In Holmes, the Gauntlets of Ogre Power refer to "an ogre (18 strength)", suggesting ogres have 18 strength. Strength scores for humanoids were elaborated in the 1E Dungeon Master's Guide (1979, pg 15), which also listed ogre strength as 18.

     The DM of the group I play in (1E/2E hybrid, currently going through T1-4) uses roll-under d6 stat checks. 2d6 if really easy, 3d6 average, 4d6 hard, 5d6 extremely difficult etc. He'll sometimes require a 3d6+1 or 3d6+2 as a modifier to make it a bit harder. As a player, it's fun to roll a handful of dice (despite the fact it means you are more likely to fail). These are more often used for players than monsters. I asked on OD&D Discussion where this system originated, and 3d6 (Bruno's Demise) replied that he first saw it in The Halls of Beoll-Dur module in Dragon #41 (Sep 1980), which has:

     "[T]here is an original procedure for saving throws which is used in some locations... roll 3, 4 or 5d6 (the number of dice varies) and subtract one point from the dice roll for every two levels of experience the character has attained. Compare the resulting number to a specified ability (this also varies), and if the adjusted dice roll is less than the character's score for the ability in question, the saving throw is considered made" (page M1).

     Looking through the module, these are used for "new" forms of stat checks rather than replacing the traditional saving throws, and would generally only be used for characters in the adventure rather than monsters.