Stats

Armor, magic resist, mana and attack speed are the same at every star level.

Malzahar

1 star: Infect the closest 1 uninfected targets, dealing 515 magic damage over 15 seconds. If an infected target dies, the infection spreads to the nearest uninfected target for any remaining time. If all enemies are infected, this effect can stack.
2 star: Infect the closest 1 uninfected targets, dealing 775 magic damage over 15 seconds. If an infected target dies, the infection spreads to the nearest uninfected target for any remaining time. If all enemies are infected, this effect can stack.
3 star: Infect the closest 1 uninfected targets, dealing 1315 magic damage over 15 seconds. If an infected target dies, the infection spreads to the nearest uninfected target for any remaining time. If all enemies are infected, this effect can stack.