Weight: ½ lb.
Estimated Value: 3,000 gp
This figurine is a statuette of an onyx dog. If you use an action to speak the command word and throw the figurine to a point on the ground within 60 feet of you, the figurine becomes a mastiff. 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 figurine doesn't become a creature.
The mastiff has an Intelligence of 8, can speak Common. It also has darkvision out to a range of 60 feet and can see invisible creatures and objects within that range.
The mastiff understands your languages, is friendly to you and your companions and obeys your spoken commands. If you issue no commands, the creature defends itself but takes no other actions.
The mastiff exists for up to 6 hours. At the end of the duration, the creature reverts to its figurine form. It reverts to a figurine early if it drops to 0 hit points or if you use an action to speak the command word again while touching it. When the creature becomes a figurine again, its property can't be used again until 7 days have passed.
Source: DMG p169