Hero Swap

Swap Heroes every 20 seconds by default
Changeable in workshop settings

How to change it in workshop settings

In Lobby

Click SETTINGS

Then click WORKSHOP SETTINGS

Then change this Value to whatever you want to change the timer.
It maxes out at 120 seconds (2 minutes)
Note: it will only support seconds, so if you enter "1" it will run every 1 second.

If you are already in the game there is just one extra step...

Just click Show lobby