Twisted fate is squishy and shouldn't go into a fight by himself unless you're using his mechanics properly.
He focuses on attack speed and ability power. His Passive grants him gold (Iirc) on enemy kills. Just a bit of extra. His Q shoots out three cards, his W brings up three icons which rotate. You have to hit the button again to stop the rotate on the one you want. Red is an AoE on next basic attack, Blue heals mana on next basic attack, gold stuns enemies for a short duration on next basic attack. Then the E is a passive which after 4 (I think it's four) he gains an amazing damage boost with the right stats on the next basic attack. His ultimate is a teleport. Activate once to begin it. Activate again and select area to begin teleporting.
You have to use him properly otherwise he can be shut down very easily. I play a lot of Twisted Fate (Or did) and he is pretty amazing if you know what you're doing and you're not shut down and get the gold (allies taking kills, or enemies not letting you get kills).
I usually build
Sometimes I go off and do other builds to. I once did a pure AD build on twisted fate which was fun with his passive E XD
Plus, he is a Marksman/Mage.
Also Corki isn't 1350. If you're willing to save though a lot of people like Corki. If you're willing to save (I already bought him so not sure what he is now) Varus is a pretty good marksman. He is one of my mains.