The Hollow Earth
Skull Sigil Coin
Once per day the sigil can be focused on for 1 standard action and laid face up by a PC. If placed hammer-side up, an incorporeal gavel appears in its owner’s hand (STR damage, FORT save halves damage) for one round. If the gavel is dropped for any reason, or when it successfully hits a target, it vanishes for the day
If turned skull-side up its wielder becomes incorporeal for up to 5 minutes. While under the effect of this aura, the owner can pass through up to 10’ of any solid object unhindered (they may not do anything else while in transit and if they end their move inside a solid object they are crushed, taking 5d6 damage per turn).