As malzahar, When no team fights are occurring, go to a side lane and push. It’s important that you continue to farm during the mid-game so you can get your items as quickly as possible. Do not just stay mid if you can’t get anything done.

After your bot lane has moved to the mid lane, rotate to the bot side of the map or somewhere else on the map so you can continue to farm and gain XP. 

Play around your Ultimate R in the mid-game. It is an incredibly strong tool that can help you get a kill advantage. With the numbers advantage, you can then make the call for Baron or siege a nearby tower.  As malzahar, When no team fight occurs, go on a side track and push. It is important that you continue to grow during the middle of the game so that you can get your items as quickly as possible. Don't stay just in the middle if you can't get anything done. After your bot track moved to the middle track, turn to the bot side of the card or somewhere on the map so you can keep closing and winning XP. Play around your ultimate R in the middle of the game. It's an incredibly strong tool that can help you get an advantage of killing. With the advantage of numbers, you can then make the call for Baron or seat a round nearby.