"Sturdy nails make for sound sleep."
—Cosper Lowe of the Silbern Guard

Boarded Window

Creatures attacking you get -1/-0.
At the beginning of each end step, if you were dealt 4 or more damage this turn, exile Boarded Window.

Innistrad: Double Feature

Innistrad: Crimson Vow

Boarded Window's triggered ability checks the total amount of damage dealt to you during the turn. That damage needn't have been dealt all at once, and Boarded Window needn't have been on the battlefield at the time the damage was dealt. Boarded Window doesn't take into account any life that you gained this turn.