Use once as a free action: choose an empty center square (d4, d5, e4 or e5). Enemy pieces cannot end a move there for your opponent's next turn.
You draft Chairs on Tables in either mode. Free action: you choose when to use it, and it resolves without costing your turn.
As a item card, it is a one-use consumable, drafted in either mode.
“The center is closing early tonight.”