Before I knew it, age had caught up to me well and good. Gray hairs, aching joints, everything. But I couldn't just sit around when I needed to resupply. Having immediate access to my regular providers became invaluable, though they did ask me to give advance notice for my arrivals. I suppose I would also be displeased if a friend appeared at my doorstep just past midnight. 

- Magnus Cadbury, Proprietor of The Gilded Hart

A stick of arcane chalk at the tip of an ornate handle, brimming with transportation magic. A tool for one to visit and accommodate friends from all corners of the world.

Mark Threshold. As an action you can sign your name onto the threshold of a doorway you touch. When you do, this chalk becomes linked to that doorway. If you use this property while it is already linked to a doorway your signature disappears from that doorway and the link is broken. You can immediately sense ifa doorway linked to this chalk is destroyed or your signature is erased from such a doorway.

Door Stride. As a bonus action you can draw a portal on a floor, wall, or ceiling When you do So you choose its length and width, up to 10 feet for each dimension and the portal opens to a doorway that this chalk is linked to. The opening lasts for 1 minute or until the chalk passes through it to the other side, at which pointit disappears and the drawing is erased (if a creature is in the opening when the doorway closes, the creature is safely shunted to the nearest unoccupied space).

Once used, this property shouldn't be used again unti the next dawn. Each time it is used again before then, the chalk has a cumulative 25 percent chance of not working and crumbling into nonmagical dust. When this happens your signature disappears from any doorways linked to this chalk.

Very Rare Variant: This item can be linked to up to 3 doorways by the Mark Threshold property, and if you use this property while it is already linked to 3 doorways you must choose one link to replace. Your signature disappears from that doorway and the link is broken.