Some guesses, a fear and an observation.
I'll start with the observation first:
Keep in mind what this is. Those were 4e stats on the back of a minis card many months before release, when the PHB isnt even really final and the MM is no where near final. Please dont presume that those are even close. Those who remember 3E release remember how some monsters were trickled out AFTER they had completed the MM and those were still wrong. In this case, we arent even that far along. Its a nice glimpse. And we are all ready to tear it apart to try to figure out the system behind it. But I suggest that we draw big picture inferences from it rather than try to deconstruct the math behind it.
Guesses:
1. Those stats are not all of the things you will see in the MM. I have to believe things like the spined defense etc will be in the final monsters. they just werent there for stats for miniature purposes.
2. I think I know what is up with the "skirmisher" designation. I think they want to make monster design using a "skinning" theory. I'll explain what I mean. I think for each type and subtype (humanoid skirmisher or beast brute or whatever) they will have a set of stats and abilites all laid out in a grid. Then, each monster gets "skinned" with what makes that monster unique. For instance, you want a 10th level orc brute, then go to humanoid brute chart, cross index 10th level and there are your monster stats. Now pull up Orc in the MM and add the special Orc abilities, like say "Axe Wielder" that gives them +2 damage with an axe or whatever. Or maybe gnolls get "Pack Tactics" that give them +2 circumstance bonus to attack when 2 or more are attacking a single creature, whether or not they are flanked. That sort of thing. Now I dont know if we will ever see this "table" that I talked about, but my quess is that something like that is underlying monster design in 4E, which frankly I think is awesome. I love the idea. For instance, I would expect to see the spined devil work like this: it is a immortal humanoid level 6 skirmisher. so go to the immortal humanoid table and cross index skrimisher with 6th level and there you have it. those are your stats as a baseline. then you add the things that make that monster unique. it is a devil, so add whatever that gives you. it is a spined devil so add its special abilities, such as spine rain and spike defense and its other abilites. and voila there you have that monster.
3. Poison will be damage over time. Ability damage is a total bitch to calculate on the fly. It changes skills and everything. It sucks to do right. It stops play for massive recalculation. It is "un-fun" and a slow down. Personally, I thought 3E poison damage was one of the worst parts of the game. I liked the idea, but the implementation and the workability at the game table blew. I think the new designers are totally fixated on workability of the game at the game table. I think that is an admirable goal.
Fear:
1. I really hope I am right about the fact that the spined devil will have more abilities than the spike rain. Its a cool ability. And I like that they beefed it up. But I dont like this "one trick pony" way of looking at monsters. I dont want to see other cool abilites go away just to make the monster more easy to run. This fear of mine started when I read Mearls' articles on the ogre mage and the rust monster. I get the idea of trying to boil the monster down to its core. But the logic was all wrong--too many abilites, cant use them in an encounter, cant get them all off, too low level, etc. Monsters are more than "combat obstacles" in D&D. They are often story points. Sure, maybe alter self has no real impact on the battlefield. But it sure helps me tell a story with that monster. It helps me know what its lair is like.
Here is a quote from Mearls' article (now remember, I think Mearls is a stud, I just disagree with this thinking that it is all about how a monster works on the game table. There is also the whole adventure design and story element to consider):
Now comes the ogre mage's offensive spell-like abilities. Sleep still has a HD limit, making it a poor choice against many parties. Charm person just clutters the list. The ogre mage rules by intimidation, not by magic. Cone of cold does lots of damage, but it might be hard for the ogre mage to avoid catching its Large-sized ogre followers in the cone. Finally, darkness covers the same ground as invisibility in that it conceals the ogre mage. It might prove useful if the standard ogre had the Blind-Fight feat, but without it the spell can cause more trouble for the ogre mage and its followers than it solves.
To replace these spells, the ogre mage gets lighting bolt and swift invisibility, both usable once per day. Swift invisibility allows an already endangered ogre mage to escape or to make a quick sneak attack. Lighting bolt deals good damage, plus as a line the ogre mage can thread the spell through its followers to hit the PCs.
I just dont agree completely with this way of thinking. I'm worried that perhaps 4E is taking this to the extreme--if it doesnt come out on the game table who needs it? You saw that mentality with the Dungeon Delve stuff recently. They were cutting spells and abilities right and left because they were too hard to use for casual DMing in the delve environment. That is not my D&D. D&D is not a one of ready to run no prep wing it game. It takes some experience and prep. Great DMs can wing it, yes. But the game shouldnt be stripped down like I am afraid it is being stripped down--give that monster one cool ability and let it use it several times in my view is not ideal monster design. I get why that might be a goal--make it easy on the DM. But this is D&D. Smart people play this game. Even smart kids play this game. I hope I am wrong, but I smell a trimming of abilities and I'm not sure I like it.
I cant believe I am saying this, but it isnt all about how the monster works in combat. I really hope i am wrong, but that is a fear I have.
Clark