Slap ladders on one file: for 3 of your turns, your rooks, bishops and queen may slide straight through enemy pawns standing on that file.
You draft Siege Ladder in Buff mode. Free action: you choose when to use it, and it resolves without costing your turn.
As a movement card, it changes how one of your pieces is allowed to move.
“Pawns make excellent rungs. Do not tell them.”