Dig Deep your Heels!

The beast roars as pig-iron spurs dig deep into its
flanks, driving it forwards in a maddening rage.
You can use this command ability at the
start of any phase. If you do so, pick 1
friendly BOULDERHEAD HERO that
has a mount.
Until the end of that phase,
use the top row on that unit's damage table,
regardless of how many wounds it has suffered.