On Sunday my group was largely AWOL. So, the few that remained decided to try a core group of 4 v. a Colossal Red Dragon. The two players each made 2 characters using the DMG, Player's Handbook and the Alpha 2 rules. The Colossal Red was from the Monster Manual.
I made a halfling Rogue and a halfling Wizard... so, my comments at level 20.
The Wizard:
I went with a generalist... because the metamagic mastery was too good to pass up. I generally don't mess with metamagic feats because I hate to sacrifice spells for guessing I'll need a quickened something or a empowered something else. As it turned out, I did have a couple spell slots free to do that, but not many. Being able to cast Mage's Disjunction (which my GM wasn't sure about it's application... if it required a dispel check for each spell effect in the area as a targeted dispel (so CL 10 v. 11+CL to dispell the effect) or if the effect just ends. He ruled that it was like dispel magic, so I had to make the checks. As it was, I was able to dispel a few things including Fireshield... so then a quicken empower a cone of cold to take advantage of that worked out fairly well. Looking back on it, I should have used Polar Ray... but I forgot I had the spell until later (problem with level 20 1-shot characters).
The other abilities... I used Shield (had 10 uses of it, so that was a given) to get the AC up. As it was, with the bonded staff (staff of power with defending and +3 added to it for a +8 to my AC), I think the wizard's AC was higher than anyone else in the party.
I also used Fireball as a school power due to the low reflex save... to burn off mindfog that had surrounded the party... the low reflex save plus the resistance 30 we had for fire guaranteed no one took damage, but the mind fog was gone. (For those interested, the DC for the Fireball was 13... Charisma of 7, plus 2 from Mastery of all schools).
I was also able to use the crafting rules to great effect. This is the first Wizard I've played were I've taken a craft feat... and thus was able to buy most of my gear at half price.
Wish - I used Wish on both of my characters (thus the 7 charisma on the Wizard). I'm not sure that the -1 to one stat is a particularly good idea... it really is just telling the players to take their dump stat and drop it 1 to 2 points. (for both the wizard and the rogue, charisma was the choice).
Magical Items - Neither of my characters used every magical item slot. On the wizard I had 2 gloves of storing, a headband of Int/Wis +6, a Belt of Dex/Con +6, Bracers of Armor +8 (kinda' kills the evocer's special ability), a Cloak of Resistance... and the Robe of the archmagi (which was basically for the bonus against SR). No boots, no hat, no goggles or things on my eyes. I did have a couple rings, and an amulet of natural armor. My point of bringing this up is that I have 4 stat boosts that could have been placed on any number of items and left me with the exact same equipment choices.
The Wizard spent a lot of time dispelling the Dragon's magical effects. Looking back on it, I should have prepared more dispels. I needed a 5 to get over the SR... and couldn't do it more than twice the entire game.
The Rogue:
Biggest problem of going up against something colossal is getting around him to flank. The Rogue spent a lot of time moving into position to have the dragon teleport away (the wizard's attempt to lock the dragon wasn't of a big enough area to have any practical effect). When the Rogue was able to sneak attack, some questions came up.
With the crippling strike, is that -2 strength every sneak attack or just once?
With Bleed does that increase every sneak attack or just once? For example, if I was sneak attacking with a full round action, would that be bleed 10 for each hit (of potentially 6 hits) or only the first hit?
The Slow Reactions was a great addition. Between Slow reactions and Mobility, the Rogue never took an attack of opportunity.
The Opportunist ability worked out fairly well also... most of the time I would hide behind a rock, then run out and attack... the Barbarian would then move up to attack (and flank for me), giving me 2 chances to hit/sneak attack in 1 rnd, where otherwise it would only have been one attack.
I had gone with two weapon fighting... but only used the second attack once in the entire game. I was tempted to take one of the 2-wpn fighting feats from the Alpha rules... but I didn't want to lose the AC bonus from Dodge for the slight bonus to hit, so I passed.
The Dragon focused its attacks on the barbarian... and after about 7 rounds of combat, dropped the barbarian. The Wizard, Cleric and Rogue had taken some damage but not much. The problem was the Wizard was running out of spells over 4th level that could do anything and the Dragon had a globe of invulnerability up that survived the last dispel attempt (I used the staff to cast a second Mage's disjunction...but only dispelled 2 effects).
The dragon decided to cast Feeblemind on the cleric... whose Reflective Shield sent the Feeblemind back at the Dragon... who then made his spell resistance check, and then failed his will save. At which point, the dragon had an Int and Cha of 1... and the GM called the game.