Malzahar vs Cho'Gath Mid Matchup
Malzahar Mid wins 50.7% of 404 Low Elo games against Cho'Gath Mid, -0.3 points vs expected, 2-patch window 26.19-26.20.
Researched on LoL patch 26.20. Tips are written to hold at any rank; stats come from Low Elo ranked games up to patch 26.20.
How to play as Malzahar
Keep your distance while Cho'Gath's Rupture(Q) is available, and avoid standing beside a low-health minion while Malefic Visions(E) is active; when it dies, the effect can transfer onto you.
Void Shift(P) protects Malzahar from Rupture(Q)'s crowd control while its protection is active, so Cho'Gath needs to damage the passive away before relying on the knock-up.
Malefic Visions(E) transfers from an infected unit to a nearby target when the unit dies, so Cho'Gath can catch the damage if he stands close to the wave.
How to play as Cho'Gath
Use Vorpal Spikes(E) on nearby minions to pop Malzahar's Void Shift(P) without committing early; once the protection is gone, look for Rupture(Q). Use Q on his Voidlings to clear them and recover health and mana.
Rupture(Q) can clear Malzahar's Voidlings(W), and Carnivore(P) restores health and mana when Cho kills them, cutting into Malzahar's wave pressure.
Sources
These notes come from r/ChoGathMains, checked against the champions' abilities.