Spike Trap is a unique trap block found on the floor of the Loft room in the Wight Fortress. It will spasmodically display an open 'active' texture on its top instead of its normal one, indicated by the hollow holes; it will not turn active if the player was standing on it before becoming active.
During the time that the block is 'active', spikes will protrude out of the block should a player step on it. These spikes will deal 2 () damage for two hits when stood on before retracting temporarily. In addition, should the player try to place blocks over the Spike Traps, even if they are not showing the 'active' texture, the spikes will protrude and destroy the block, dropping it if it can be dropped. The spikes create a sort of puzzle that the player must navigate to break the four Item Cages in the room to obtain the Shockwave Sword.
Do note if you try to mine it that it is protected by the fortress.