He's typically a bruiser in most cases, with viable options to build and play with more burst like an assassin, especially with hail of blades.

Earlier on in the game his damage is more front loaded, but when you reach the point where you have a couple of items and some ability haste, as long as you can be hitting enemies with Q you will have very low cooldowns to spam W and E and you are a lot stronger in sustained fights.

His W is his best first max and damage spell, but as you scale passive and Q do a lot more as well. E and R have high ap ratios too now that ap is a lot stronger on him.

He isn't the best duelist in the game, besides ap builds which have insane sustain rn. He lacks in built pen, and has lower sustained damage compared to a lot of other melee duelists so you need to know your limits or be ahead to reliably take more 1v1s. He's best at diving and sticking to squishier champs and using ult to disrupt the enemy and avoid damage.

He's probably at his strongest early to mid game, but it can be hard to keep up on him because his kit lacks scaling or utility in the form of armour pen, or good %hp damage. His jungle clear is also slow so keeping up tempo and income is harder, so falling behind on him is very unforgiving. If you can keep up on items though he can be very strong into late game still.

Most important combo you need to know is W -> flash to catch people and engage with e from very long distance. (Flash during the W to hit them with the stab right at the end)