Hey there, this guide is about ap tryndamere, who become in my opinion really viable after the last patch and who is extremly fun to play ;)

Dont ever take Greater Mark of Magic Penetration with any sort of tryndamere, its completly useless because his whirl deals NORMAL damage, take Greater Mark of Attack Damage or Greater Mark of Desolation instead!
For seals I get health per lvl because theyre 1.: just great and 2.: give you some of the survival you want to have
Glyphs and Quintessences at ability power what else =P

Flash and Ignite or Flash and Ghost, compared on what youre focused on, more dmg or a better chance to flee/ catch.

Aswell as with the runes dont get the magic penetration thing because its useless!
I take this set of masteries because it gives you survival, ap and the Ignite boost.
If you want to get Ghost instead go for 8/21/1

Starting with Amplifying Tome and Health Potion gives you a bit of damage and great lane-staying power, because that way you can heal about 100 every 10secs with Bloodlust and have a pot for whenever you need one :D
Your first item should be Sheen because it gives you ap and every time you whirl or heal you get an stronger autohit after that.
After that get your Mejai's Soulstealer and Boots, more ap and cdr -> more kills -> even more ap...
Lich Bane is an essential item for you if you got it youre somewhat unstoppable, E -> Autohit -> Heal -> Autohit -> E -> ...
Rabadon's Deathcap is of course for more dmg and heal

I skill Spinning Slash first and after that Bloodlust, to get the higher amount of dmg, instead of maxing Bloodlust second you could also max Mocking Shout
if your enemys are mainly focused on ad and you have problems with survive