This is my first build that i am writing, dont flame me if you dont like how i wrote something or the way i set things up. i dont mind having suggestions made on what runes i should use or what items work better for trynd, but remember that this is my build and it works pretty well.

Pros:
High damage output with his crit chance
Can navigate through walls to make ganking easier
Ulti prevents you from dying for 6secs and increases damage output at low health

Cons:
Farm dependent (expensive item build)
vulnerable to thornmail if you dont have banshees veil
No damage output from skills, basic attacks are his dps

I went with armor penetration marks, to allow me to deal more damage to the tanks and squishies early game. You can switch these out for crit chance or crit damage but i prefer the armor pent because early game no one has alot of armor and you can deal full damage to the enemy.

Yellows i went for attack speed to increase my dps early game. I found that the attack speed yellows really help as you can farm minions alot quicker and you can attack the enemy alot more in a short period of time. These coupled with the armor pent reds make for a really great combo. You will be attacking them alot more for the full amount of ur attack damage and crits.

For blues i went with cooldown reduction to allow me to get my ulti back faster and to use my bloodlust stacks more often. This pretty much allows you to constantly have your bloodlust spell active for whenever you need to heal. If you took the crit chance reds instead these runes help alot as you will always have your bloodlust stacks and your bloodlust spell at all times. Giving you a constant heal effect.

I went for the typical ad rune set up, going 21 down offense and 9 down defense. Now most of you are probably wondering why i went for the 9 down offense instead of 9 down utility. Well the reason i did that is at the beginning of the game with the hardness and resistance masteries i can take more damage while dishing out more than i am taking. The 21 down offense well those are pretty explanitory, grab the crit chance mastery and get the ones that give you more cooldown reduction as well as the ones that increase your attack damage.

Get your brawlers gloves first, this will increase your crit chance allowing you to get your bloodlust stacks even more. Get 2 health potions as well when u get your gloves, these will allow you to stay in lane longer unless your getting harassed alot by the other team.

Then get your berserker's greaves your first time recalling, make sure u get them all at once instead of piecing it out seperately. Of course you may not be bale to do this if ur getting harassed constantly so only piece it out if you have no other choice. This will increase your attack speed making you crit more even if you dont have crit chance runes.

By now you should be dealing decent amount of damage and maybe have a few kills, this is when you go buy a zeal, no explanation needed here. More crit chance and attack speed as well as a little bit of increased movement speed. If you have enough buy a vampiric scepter. Lifesteal coupled with your bloodlust stacks and ur ulti make you almost invicible at this point.

Now this is where you get to make the choice of which item you want first. You can either finish off your zeal into a phantom dancer or you can go and buy your infinity edge. Both of these are great choices but i prefer getting my phantom dancer first. More attack speed and more crit chance. you can get infinity edge first which would make your crits do more damage and give you more attack damage as well as more crit chance.

Now you can get your bloodthirster, this will be your main source of healing. the lifesteal effect as well as an increased 60 attack damage makes this item great for ad champions like trynd. Stack this as quickly as you can. The faster you have this stacked the less likely you are to die in fights.

Again you have another choice of what to get first. This choice is strictly situational, if you are getting focused with alot of CC or their tanks has a thornmail already you should get your banshees veil first but if the enemy doesnt have thornmail or doesnt have a tank then i suggest getting black cleaver. Black cleaver reduces their armor with each attack, up to three times, making you hit more and kill them faster. This item also give more attack speed and more attack damage, perfect for trynd.

For summoner spells i generally get ignite and ghost. Ignite is a great finisher if you used at the right time. If you can get to the champion as they have flashed away this will make sure that they die. Just remember to cast it when they are low so you dont miss your chance at killing them.

Ghost is pretty self explanitory, gives you increased run speed. This coupled with your mocking shout slow makes it almost impossible for people to get away unless they have flash or a flash type spell like shacos decieve or ezreals arcane shift.

All in all tryndamere is great and fun champion to play, in my opinion. He has high crit damage when coupled with his bloodlust stacks and infinity edge. If you are facing a squishy with no armor you can pretty much 2 shot someone. Ive done it to karthus players so many times as well as irelias. Trynd is very much dependent on tiems and team play early game until he is lv6 at which point he can destroy enemy champions. He is also very vulnerable to thornmail unless you get more lifesteal or a heavy magic resistant item like banshees veil or force of nature