I thought I'd share my build since it's been doing well for me in T3.
Build: http://us.battle.net/d3/en/calculator/wizard#WcQSOj!UZh!YZZccc How I play it
Keep Arcane Orb up; this instantly casts without time or animation so you can hit it whenever needed. Keep your buffs up of course! This is a very tanky build so you can stand in the face of things, but you want to move out of things that wind up and hit with a stun, and you don't want to stand in things if possible. I can stand in Belial's face in T3 and not have to move until he starts the bomb spam.
Teleport is really an optional choice, if something else is better for your playstyle go for it. I use that Familiar rune because everything will be clustered around you and it turns out to be a lot of AOE damage. I use those passives for survivability and the snare helps with some things that choose to run.
When attacking, I try to round up all of the melee and start triggering the bombs. This is important to figure out because just being close to something won't always set them off; you can be as close as possible to some enemies but at some angles you won't trigger the explosions. You will need to figure out what each enemy needs by moving around. Spam Spectral Blades, press Arcane Orb every 3-4 seconds. AO casts will not interrupt your SB spam. If things get bad (usually because of a Waller with some sort of AOE), Teleport out. You can also use Teleport to get into the middle of groups for more AOE damage if the situation calls for it.
Weaknesses Xah’Rith absolutely demolishes this build. I don't believe it's a problem with how I play it but because you spend the entire fight vs him slowed, while he naturally runs away, and with the split and teleport it's extremely hard to do real damage to him before being overwhelmed. Anything that creates Walls can be a problem as well because you are going to want to be within melee range already. Things that hit extremely hard in melee are usually dodgeable, though. AOE proc elites can be trouble because they will block you in and then drop all of their AOE right on top of you, making movement impossible; this is why Teleport is used, but it has a cooldown.
This looks like that Orbital Bombardment build
While we both use the orbiting orbs and the legendary neck, my build is centered around really being in the face of things. The double shielding procs help with survivability at the expense of some damage; if you have a LOT of Toughness you could of course change those. I have 1.3m Toughness so I need them. The main difference is that his build is focused much more around being Glass Cannon and making up for the extra damage taken while mine is all-in survivability while trying to increase your damage with gear and playstyle. Grouping things together and learning how to trigger orbs can be massive damage.
Moonlight Ward - The proc adds more explosions, you will be constantly spawning these and they will constantly be going off.
Fragment of Destiny - As high Spectral Blade bonus as possible
Desired stats on all gear - % arcane damage, % Spectral Blade, % Arcane Orb, Attack Speed (if you have huge amounts of crit, stay with that).
Attack speed vs crit
I personally stack attack speed because the main part of the build is spamming SB. However, I can absolutely see an argument to only stack crit since AO and the proc orbs don't benefit from attack speed. It's up to you to figure out what works for you.
If you have any questions or comments or suggestions go ahead and ask! I think this build is very strong even with its specific weaknesses.