Does a creature provoke opportunity attacks when it leaves a threatened square adjacent to an enemy by burrowing?
See this closed question for prior discussion on the topic of burrowing.
Exception does not include burrowing. But more importantly:
The interrupt (not a reaction) is key. So before the burrowing happens, the
There is some clarity in the power description:
The reason to prohibit shifting during burrowing is to explicitly allow for
... most likely ... No
This is assuming the creature is in an adjacent ground square, not in an adjacent open air square, in which case the answer is ... Yes
Unless the square of ground the monster is burrowed in is transparent, there is no