The Death Mask's armor counterpart is the Dark Armor.
The Death Mask is a grey mask that appears to have been carved from stone in the shape of a skull. There are two holes for the wearer's eyes and carved fangs on the bottom edge. The top of the mask features a mass of red feathers, and its sides bear polished bone spikes with thin red-brown stripes.
The Death Mask gives a massive boost to Attack, Dark and Death & Doom resistance, at the cost of Accuracy. It also buff the user's Attack after getting hit by a powerful attack.
Epic Battle Fantasy 4
Found on the Battle Mountain, in a hidden chest on the Rainbow Rafflesia screen, requiring to push the blocks onto X-marked tiles for it to appear, beat the boss and reach the chest from the next screen. The Stepladder is required to this far.