Anti-Portal Block

The Anti-Portal Block is a block that prevents portals made from the Portal Gun to form. This can be useful for map makers who want to make some places inaccessible by portals. They are sold by the Traveling Merchant for 1 each. Like other blocks, they are stackable up to 999 items.

Trivia

 * The sprite of the Anti-Portal Block is a reference to the 2007 puzzle-platform video game Portal, where the darker-colored tiles disallow portal placing.