I've seen a few Dominion Teemo builds that use the new items, but I still prefer to use the original items with him. The items that I use buff his Blinding Dart, Toxic Shot, and Noxious Trap.

I play Teemo as an ambusher/Nuker because he is able to run into battle, deal high dmg, run into a bush that he just shroomed if they follow, and repeat.

To start with, I get Ruby Crystal (less squishy and builds into FM), normal boots (more MS and cheap, builds into BoM), and amplifying tome (+starting AP and builds into Sheen). I start with these items because they ALL are built into other core items without having to sell them later on.

The only AS that is built is in Nashor's Tooth because it gives 50% AS, 20% CDR, and 55 AP. This makes Teemo's ability to harass much better since it will allow toxic shot to be stacked without sacrificing extra dmg from the rest of your abilities by choosing a different AS item.

Rabadon's Deathcap is a MUST have 1st built item because it gives your blinding dart, toxic shot, and noxious trap a 140 + 30% AP boost. Usually you will get this completed around level 8 if you are neutralizing and capping points as well as getting some kills.

Boots of Mobility is the second item to finish as you will want to run as fast as you can between points. This coupled with your Move Quick at level 1 will have you running faster than almost every champ before level 10.

Lichbane is the third item to fully be built. If you have to ask "Why?", then I will have to kill you with teemo so you can see why. Lichbane's passive from Sheen gives Teemo +100% AP damage to the next normal attack after using an ability. This translates to "Walk out of a bush, blind shot, normal attack, move quick, normal attack, drop shroom, normal attack, and if they aren't dead yet, blind dart should be off of CD by this time".

The other 3 items are more situational items. I would build of Stinger from Nashor's Tooth before the rest so you can take advantage of the AS and CDR from it, then build out Frozen Mallet to make Teemo less squishy before finishing Nashor's Tooth. You will almost never be able to finish Void Staff because Dominion is based off of short matches.