I personally always take TP and Flash unless its a match up i can easily abuse, then i will take ignite. I try to farm up and play for mid/late game and use my TP to make a play on other side of map.

Conqueror is just too good right now until its removed.
Triumph will save you on ignites, brand passive, liandry burns, early fight and minion aggro after getting your kill.
Attack speed 100%, do not waste time and stats with tenacity on tryndamere, you are one dimensional, and there is way too much CC in the game for tenacity to really be relevant on him.
Last stand, works well with your passive.

Resolve 100% of the time because Trynd vs New/Meta picks top just hurts and is too hard without resolve, it makes your lane phase a lot easier, as well as providing Demolish for late game splitting.

Attack speed, Adaptive force. always. as far as last one, go armor into ad and MR into AP. i like going the health vs tanks that dont have AP poke.

I never start Q, not even into poke champs, i prefer E. if you allow a ranged champ to bully you level 1 to the point of death or burning flash, then what good would Q do you, take E for cheese engage, or to spin away. against ranged i use the bushes, walk up(take the short poke) auto a minions and spin through the others that are low enough to execute with my spin back towards my tower. you get level 2, you have Q to sustain now. i NEVER when playing passive level 1 against a range, have been dropped below 70% health, which i get back instantly at 2.

I start Long Sword, and Refillable Potion into every match up. I refuse to start dorans or anything else, due to my aggressive/snowballing play style, it allows me to finish items faster without the Dorans 450g and constant health pot purchase deficit.

Cull - I never used to use this item until i started playing more Riven, vs tank match ups, same ordeal, if someone is playing super passive, and refuses to fight or trade, i will grab a cull and focus fully on a farming and a TP play.

if i have the 1300 Gold, i will go Zeal vs Non Tanky Champions, and i will go B.F. sword vs tanky/bruiser champions.

Serker Greaves - mobility early, PLUS the attack speed from them is just too noticeable to pass up, great duel item and great item to dodge skill shots and cancel peoples autos with.

Vamp scepter - i will get if its all i can afford. also, if im taking short trades, or, i am against a ranged vs melee match up to help me sustain.

Tiamat - i use against Pantheon or Shen to shove them in to stop global ults. Also this is a fantastic first back item vs a Yasuo, it works very well with the cleave on auto attacks vs minions to drop his passive shield. This is also good after cull to shove in passive laners quickly to roam and hope to make a play mid or in the jungle. push and roam boys, dont stand still in lane.

Zeal will go to Shiv, notice tiamat is gone, when i build tiamat, i usually sell it around my 3rd - 4th item to complete something i need. I prefer shiv, small wave clear (can be balanced with spin dmg), AND a big POP on that first crit, great for dueling. and amazing for quickly eliminating a ap or ad carry.

Gun Blade i prefer over bork for the active. not only the active, but the revolver, Spin(e), and shiv. is pretty nasty burst. and it scales well with the AP in this build

Essence reaver is for CDR, 20%, and the Passive. Okay, when you ult on tryndamere, you are at your strongest point.. Remember season 8, AP Wizardmere, just SPIN SPIN SPIN. Once you are at 40% CDR with Essence reaver and the scaling AP in this build, your spin is on basically 0 CD SPIN SPIN SPIN WIN mode again. =)

Nashors tooth/Black Cleaver... the way i decide between these two, is, Tank team or squishy team, and if i need to be a meat shield longer in fights. Cleaver for tans/meat shield trynd.. nashors for hyper carry.

then of course IE last. UNLESS i some how stay out in the rift long enough to some how pinch the gold to buy it straight out on a back.

If you would like to get a more in depth guide or idea of what i do on tryndamere, you can add me on SynergyXO on NA. or my discord SynergyXO#6542 and i would be more than happy to help you.