katarina's laning phase is really hard and everyone can punish you pretty easily, you need to survive the laning phase by not falling behind on levels and waiting for your item spikes, farm as much as you can with your q last hitting.Katarina is really good at roaming to stack your dark seal.You can also use tp to surprise the enemies in fights so you can get easy kills and help your team of course or just back and tp back to your lane with full hp and extra items.You can go dorans blade for kill pressure in lane but it is pretty important not to die.

One usefull tip i can give you: you can q on minnions to set up your dagger and then e at the dagger then w(wait for for your w's dagger to fall) pick it up and then e out. YOU NEED TO WAIT FOR W TO PICK IT UP because your e does not reset with only your q (you have another 2,5 seconds cooldown)

If you survived the laning phase, congrats now you can start to carry.In mid game you need to fight skirmishes if you think you are capable of winning them and generally try to take objectives with your team.Its pretty important though to side lane so you wont fall behing in XP and gold.

you need to be extra careful in late game because one mistake can make you lose the game.try to play with your team and its important NOT TO START A FIGHT ALONE because you are really vulnerable and squishy so you will die easily.Always try to make plays if the enemy team doesn't have their stuns up.

PROS:

1)really low skill floor and high skill ceiling
2)really strong
3)fun to play


CONS:

1)weak early game
2)easily punishable
3)a lot of bad matchups