Tryndamere is a insanely powerfull top laner and split pusher and can have a large teamfight potentiall. His biggest counters are people with overtime damage like teemo or twitch. To counter this all you need is cleanse. Also if you fight baron the baron will lower your attack damage similar to how the dragon lowers your attack speed. This makes cleanse a very useful spell when facing baron.

Most people when playing trynd get very aggresive items but I havent seen anybody actually go this much into damage. Unless somebody had Thorn mail a couple warmog's armors and a guardian angel there not surviving your onslaught of physicall damage. Also with the full build and the crit part of tryndameres passive allows you to get over 100 percent criticall chance. With that and infinity edge you can mow through anything in no time.

Most runes are pretty standard and just have full damage lvl 1 armor lvl 1 and scaling magic resist since you don't usually have to worry about magic damage early. But most don't have scaling damage or critical damage. These massively help you late game as they give you a lot of extra damage and since you get such high critical chances you want beast crits to go with it. The scaling attack damage really just helps you late game when you need a little extra damage but the non scaling ones wouldn't give it to you.

I really don't need an explanation here since these are pretty standard AD top lane masteries.

Usually when facing an oponent you want to E in and then just start bashing them. This no exception.

When farming you want to E through the melee minions to the weaker ranged minions in the back. This will give you a couple easy pieces of farm and can poke at the same time.

Tryndamere is considered to be one of the strongest hitters in the game as people don't feel the need to get defensive items since tryndamere has several defensive maneuvers from his kit. This makes him able to go full blown attack damage and crit chance allowing you to deal tons of damage in single strikes.

Tryndamere is a very strong champ but has a few things that may or may not work for you:
pro:
Generall hard to kill
High damage (especially with crit)
Higher mobility
Cons:
Can get shutdown early
can be easily countered by over time damage
high priority target so may get focused
low CC

In ranked play yu generally want to try and stay away from games where they have overtime damage or a teemo. If you see a teemo he is likely top to shut you down by heavily countering you.
You may also want to have a couple backup tops just in the case tryndamere is banned. Finally having multiple runes/masteries to help for certain scenarios can be very useful.

Champion: Difficulty/explanation

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Riven: Moderate/Be wary of her ult and if she charges retreat using E try and stay away from stun
Teemo: Difficult/will constantly blind you and force you out try and get frequent ganks
Zed: Difficult/Will likely evade you, Stay away from shadow and ult when he ults.
Fiora: Moderate/ hard to take care of try to stay away from all out fights and just go for farm.
Yasuo: Easy/Shut him down early with ganks and heavy and lighter pokes. Just don't extend fights.
Tryndamere: Moderate/Shut him down with ganks.
Darius: Easy/Just dont let him ult you when you are super low and dont have your ult.
Garen: Hard/Hit him hard early and a ocasionally gank just dont let him get too much CS
Jax: Difficult/Will be able to stay with you and stun you just play passive and get ganks.
Lee Sin: Difficult/Will likely kick you into team just try and get advantage and stay more passive early when he owns.
Pantheon: Difficult/Get hard gank and get attack speed as fast as possible to get through his blocks. get him to overextend and go all out.