Now I realize that a lot of you are going to look at this build and wonder if I'm all there in the head or not.So I will give you a quick explanation as to why this build works. People are still getting used to Trundle's extremely unique play style and to build a perfect Trundle you have to understand what Trundle should be doing.
First off, Trundle is not a main tank so you will not be initiating full team fights. Instead you will be waiting to the side while your main tank runs in. Trundle is always on the move and usually taking damage from ranged. This is why dodge is very nice as with the defensive talent it also gives move speed to chase or get away.
Not having increased exp or neutral buff duration from utility hurts but I believe the defensive talents more than make up for it, especially late game.
I use flash because any hero with a blink or anyone with flash can hop over your pillar and without flash you will be blocking yourself more than them.

I would highly suggest you start with your enemies golem. Ideally you can get your team to help you gank or team fight there. If you are alone you can simply wait till a little after 2 minutes in, smite steal it, and hopefully kill them as well. If they are not at blue then you got their blue buff for free, grats. From there I would kill your wolves, then ghosts, then smite will be up again to kill the two golems. From there take out the small lizards at red buff and head back to town. You will have enough for at least a long sword if not your full madred's. Head back and take red buff then I would suggest going for a gank. You should be level 4 and be able to pillar of filth and red buff slow some one down. After this just grab as many creeps as you can while helping out in lanes. You can also dragon as soon as you get a wriggle's and make sure to ward dragon/river as well.
Also, ganking their jungler, if they have one, is very easy if you have red buff. I would highly recommend it.

As you are not the main tank you will be hiding in brush before a lot of team fights. The idea is to wait for your team to initiate or their team to over extend.Then you can drop your contaminate on the battlefield and pop pillar of filth to separate their team.
Your pillar can make or break a fight so make sure you know how to use it before you play this hero. Try some custom games or something because it isn't hard to use but if you are bad at it your team might hate you.
Trundle's ult is GAME BREAKING. You steal tank stats and health from a given hero. This is great for bursting a tank when they initiate. It also has a low enough cooldown where you can use it for dragon and not worry too much about it not being up for a team fight. It can also be used to turn the tides if someone catches you jungling or something. Pop that and you will be hitting them much harder as well as them hitting you less hard, not to mention the health steal.
Rabid bite is pretty self explanatory. Use it as much as your mana will allow. Getting both your and their blue buff is incredibly useful. I carry around mana pots quite frequently early game.