Rules - Burrow/Burrowed

A creature with Burrow has "{t} : This creature
gains burrowed."
A creature with Burrowed may not attack or
block, loses flying, and has "{t} : Untap this
creature. It loses Burrowed". A creature with
burrowed may not be damaged, blocked or
targeted by a source an opponent controls unless
that opponent controls a creature with Detector.
A creature with Burrowed cannot activate
abilities that do not have "{e}" in their cost.