Often times when Annie reaches level 6 she will charge up pyromania so she can roam and gank. What happens after you've finished your gank and still have time on your tibbers? One thing that most pros do is to use Tibbers to control the Elder Lizard or Ancient Golem Runes. 

How to - Use alt to control Tibbers to go to any of the 4 runes on the map. Move Annie behind the walls of of the neutral mobs while running Tibbers to them directly. When you do that, Tibbers will immolate the creeps and they will try to target your champion. However, your champion will be safely on the other side of the wall. Tibbers will give you vision of the mob at the same time immolating it.


Source: https://kassadin.blogspot.com/