Shields Shall Be Splintered

A popular houserule mechanic for OSR-based systems.

B/X Dungeons & Dragons

Any time you would take damage, you can opt instead to sacrifice your shield and spare yourself. The shield shatters and is removed from inventory, but you don’t take any damage in that instance.

Notes & Further Reading:

The mechanic appears to have originated in a blog article from Trollsmyth.