I would think that burrowed creatures could dig underneath it... maybe something like:
"Shield: Uses 1
![Water :water](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/water18x18.png)
to absorb 4 damage from physical sources. Water and burrowed creatures are unaffected."
Very similar to the
![Entropy :entropy](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/entropy18x18.png)
shield. Given the duo requirement and the small limit on affected creatures, it could probably do with a small cost reduction. (after all, dissipation shield only costs 3
![Entropy :entropy](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/entropy18x18.png)
)