This gold coin, a dragon, has the face of Tymora stamped on its head side and a winged serpent stamped on its tail side. The coin has the following properties:

Heads. If you use a bonus action to speak the command word (Heads) and flip the coin into the air, the coin becomes a magic golden shortsword (+1 sword) entwined by two winged serpents when you catch it. You can use a bonus action to speak the command word again, causing the sword to revert to its coin form.

Tails. If you use an action to speak the command word (Tails) and flip the coin into the air within 20 feet of you, the coin becomes a black viper with golden wings (flying snake). If the space where the creature would appear is occupied by other creatures or objects, or if there isn't enough space for the creature, the coin doesn't become a creature. When transformed the creature is friendly to you and your companions. It understands your languages and obeys your spoken commands. If you issue no commands, the creature defends itself but takes no other actions.

The creature exists for a up to 12 hours. Once it has been used, it can't be used again until 2 days have passed. While in flying snake form, you can cast the animal messenger spell on it at will. At the end of the duration, the creature reverts to its coin form. It reverts to its coin form early if it drops to 0 hit points or if you use an action to speak the command word again while touching it.