Why? I'm confused. I'm playing a staff wizard, my initial stat array was 16,14,13,13,12,8. Eladrin makes this 18Int, 14Con, 13Cha, 13Wis, 14Dex, 8Str. At 4th level I took +1 Int, +1Wis, at 8th I'll take +1Int and +1Con so that at 11th I'll get my staff up to +3 but the rest of my pumps will likely be to Wis and I'll eventually take orb as a second implement.
The utility of both your orb and your staff mastery bonuses are increased exponentially as your bonus increases. If you take second mastery and spread your secondary points between con and wis then neither of them will be very valuable.
Your staff mastery is essentially a "turn a hit into a miss power" very similar to what halfings get(but halfings can stop a crit and you cannot though you get a guarantee). The quality of hit it can turn into a miss is a function of your bonus. The more con you have the more ability you have to stop an important attack(like some stun that would hit you otherwise).
It works the same for your orb, at low values the penalty does not significantly increases the time you keep a single enemy under a save ends effect. If you're going orb you've pretty much got to punch it. You also have to be able to use a staff(2 handed) and orb at the same time.
That isn't to say that second implement isn't valuable, but its much more for Orb wizards who have some dex and want to make sure that their precious save ends power hits the enemy that they want it to by grabbing a wand mastery. Wand mastery is also nice because the orb doesn't require you to attack with it to you and so you can worry about an orb with a good special ability and then wield a high + wand in the other hand. But in that situation you're pretty much just buying a situational + bonus to attack.
Thunderwave is very good and I frequently think about swapping out ray for it but ray has some serious utility in certain situations and scorching goes with my "fire wizard" concept. Scorching also frequently allows you to target more enemies since it's range allows a wide variety of placements. I do love thunderwave but I disagree you can simply say it's the best at-will. Depends on the situation.
The key is that not only does thunderwave have more control in the majority of the game, tie in with your strogest powers better, but as you advance into paragon tier the feats that allow you to maximize its potential make scorching burst terrible in comparison.
Thunderwave ends up(assume Wisdom of 18 by paragon tier) as a ranged 2 Close burst 4, push 5 that gives you 2 to any defense every time you use it. Yea its 3 feats, but it makes your at will stronger control than many of the push encounter powers.
The only problem with it is that "push" is defined from where you are and not from the origin of the power.(if that was the case then Thunderwave would become nearly a slide 4 power)
Now, your personal choice not withstanding does not make it not the best at will.
This waters down the build differentiation and really doesn't make a lot of sense. Not every wizard needs to have t-wave. This seems more like a "I wish it was this way so I could get better effect with my build" argument. You can't really argue it's the best at-will and then say "lets make it better".
My argument is "its the best at will but utilizing it requires the player to hamper their build in order to get that use out of it". I.E. "Strong Thunderwave should not be the perview of Orb wizards with decent dex only"
so by extension if you're in the corner of a stinking cloud, attacks against you are at -2 for melee and -5 for ranged and monsters in melee with you under the cloud only get -2.
No, the edge of the cloud can see out, nothing can see in. -5 on all attacks going in, no penalty if you're on the edge of the cloud going out. Makes it a tad bit harder to use(sticking it next to an ally does not block that enemies LoS to your friend, giving them an advantage). Just as if you're looking out from under any other concealment.
I get that it's just rarely a huge benefit and i can use the cloud for the same purpose while doing damage with it.
Yes, but only once per day. I am highlighting that you still get a lot of benefit out of these powers during other times. You can't have stinking cloud up every encounter, only once.
How much wisdom do you need? Clearly you can't argue arcane reach is mandatory? is there really a point here other than getting every feat and power with the right stats is difficult with wizards... this is a good thing not all wizards need to be the same.
Only if the other options have just as much power, and they really do not. To make use of thunderwave you really need a 4+ wisdom mod, preferably higher.
hardly the only viable build for a wizard.
Viable =/= optimal. Just as you would expect any large AOE character to dominate some encounters(encounters with low enemy levels means that the large AoE character gets more hits in, especially when coupled with high enemy counts typicaly for those encounters)