Soraka silence doesn't always work.

The bubble it creates on the ground does not always silence. For instance the last game I was in had a Zyra who GA'd. I put the silence down so when she came back up she would be silenced immediately but she still managed to get her ult. off. Maybe I dont understand the mechanics of ult's but I thought silence would keep someone from ult'ing. It is not only ults either. Thank you!

Zyra had no way of removing a silence either.