The Snakepit ring interaction with creeping frost

Can anyone help me understand why the snakepit ring is so good? I just equipped it. If I cast creeping frost only sometimes she will cast it twice, but I have to stay still, and it doesn't happen reliably. What is the difference between self casting it twice in succession when I want to unless I need to shoot and move? When it actually forks does the creeping frost ground damage stack, while normally it does not?

Confused newb :D

*Sorry...I get it now lol.