Don't be afraid of spamming skills to get your Voidlings into action.
Lay down a Null Zone before using Nether Grasp to maximize damage.
Null Zone is extremely potent against high HP neutral monsters. Try using this to get the blue buff from the Ancient Golem.
Voidlings have a limited lifespan of 21 seconds.
Avoid minion waves that have been affected by Malefic Visions. You never know when they may die and pass the Visions onto you.
Malzahar can be difficult to 1v1 if he has his ultimate up. Make sure you have enough Health to survive a round of his spells.