From the unofficial tooltip translation thread on Reddit:

>> Surecast - While active, next spell is cast without interruption, and you are immune to sleep, stun, knockback, and pulls // 10s duration // 30s cooldown
Depending on implementation, this can help get around certain mechanics such as all the tilting during Sophia.

Just wanted to point out this change (subject to change upon release) for any player looking to optimize their play. Also makes sense why Surecast is a level 48 ability now with those kinds of status protection.