Malzahar is a well-known counterpick to Katarina. He outfarms her, so she can't push her lane to go roam for kills. He has longer range on her, so he can harass better. And when she tries to dive him, he just blows his load on her with zero chance to miss his skillshots because she's right on top of him. Building a QSS won't do too much either, so long as Malz notices she's built it immediately (and any good Malz keeps an obsessive eye on enemy builds for QSS anyway). He can just poke/silence/DoT her down until she has to blow it to get rid of the MV, and he can flash in and ult. Malz can only lose if Kat is a much, much better player and he's never played ranked.

There really aren't many 1v1 matches that malzahar will lose. His high ratios, % dmg and ability to lock down an opponent with his ult means that you would be hard pressed to find a champ in the league that can survive his combo. Even tanks have to be a little weary when approaching a malzahar.

I'd say Malazhar, but Kata builds QS and it's 100% Kata.

Her snowballing needs a nerf anyway

malz can beat kat really easy if he good at use his e to farm because kat can be zone out by him and her q or e not going to have the range need to really hit him if he e farm.

it all because it a DOT move that can jump from creep to creep or champion so use it once can make you last hit easier and have it jump to a champion and do a good amount of damage.

malz wins in every way unless kat can push him out pre6

Quicksilver Sash.

Kat never gets 100-0'd in lane, and she can free farm when she finally out scales him in raw damage. Just don't get silenced.

The only thing Malz has on Kat is the ability to farm safely.

It's funny because I actually had this matchup not too long ago when I was playing Malzahar and from that experience.. Malzahar destroys Katarina.

Katarina jumps on you and starts to ult? You press W-E-R, cancelling Katarina's ultimate and killing her with your combo. *shrugs*

kat can just sit back and infinitely poke malph in lane; malph naturally will push because of his aoe abilities.

kat can just sit under tower and farm; malph will auto die when jungler comes because he has no escapes.

if malph gets his combo off on kat, kat will be fine, because she builds tanky has spell block and very good disengages.

in team fights if malph is just standing around in the middle of the fight waiting to ult kat, malph will probably be steam rolled and die in 2secs from kats team members, because he is super squishy.
or kat will just wait till malph is stunned by an amumu ult or sona ult, or wait until malph is at 75% life, and will auto die to her ult before he has time to ult her in return.