Does Swift Cast work on any skills?

[VanilleFang]

I just used Bio after Swiftcast and then Summoin II, the Summoin II was instant.

Did you make sure to cast Bio after Swiftcast registered as a buff? I've done it plenty of times where I will start to cast Raise after using Swiftcast because I'm too quick with my inputs. You have to give it a sec for the game to apply the buff.