After your 7th move, one of your central (files c through f) pawns with an empty square ahead, chosen at random, advances one square automatically.
You draft River Breakup in Buff mode. Passive: it works on its own the whole time you hold it, with nothing to activate.
As a movement card, it changes how one of your pieces is allowed to move.
“When the center ice cracks, something always floats forward.”