It says "on the next enhancing effect". To me that implies some cooldown. Could be totally wrong but depending on how often you can burn that, insofar as the enhancing spell you cast, you wouldn't usefully be able to put two enhancing effects up on your party in a timely manner anyhow.

You could be left spamming that 1 ability whenever the CD is up on that 1 barrier (read: stoneskin by a different name).