I was playing Half-bloods hoping for some easy upped cards. The AI played dissipation shield (unupgraded), and I was using a firestall with fahrenheit and firebolts. The dissipation shield blocked my fahrenheit as is normal. Then, the AI plays an upgraded sanctuary (probably doesn't matter, but...) and I attack. It still says that my attack was absorbed, and no damage was dealt, but the AI didn't lose any quanta. I tried playing another fahrenheit later, and it was still absorbed.
TL;DR version: AI plays dissipation shield then sanctuary, and it creates an impenetrable shield.