Source: Bigby Presents - Glory of the Giants

Wondrous Item, Varies

Larger and more roughly hewn than typical figurines of wondrous power, these statuettes depict dinosaurs and related creatures from the earliest days of the world.

As an action, you can throw a prehistoric figurine of wondrous power to a point on the ground within 60 feet of yourself while speaking a command word, whereupon the figurine magically transforms into a living creature. 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 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. See the Monster Manual for the creature’s statistics.

The creature exists for a duration specific to each figurine. At the end of the duration, the creature reverts to its statuette 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 a certain amount of time has passed, as specified in the figurine’s description.

Carnelian Triceratops (Very Rare). This figurine becomes a triceratops for up to 6 hours and can be ridden as a mount. Once it has been used, it can’t be used again until 10 days have passed.

Jasper Tyrannosaurus Rex (Legendary). This figurine, crafted from rare green jasper, becomes a tyrannosaurus rex for up to 1 hour. Once it has been used, it can’t be used again until 14 days have passed.

Whenever you command the figurine while it’s in tyrannosaurus rex form (including commanding it to revert to figurine form), you must roll a d20. On a 1, you lose control of the figurine, and it becomes hostile to you and your companions until it is reduced to 0 hit points, at which point it reverts to figurine form.

Kyanite Pteranodon (Rare). This figurine becomes a pteranodon for up to 8 hours. If your size is Medium or smaller, you can ride the pteranodon as a mount. Once it has been used, it can’t be used again until 7 days have passed.

Pyrite Plesiosaurus (Uncommon). This figurine becomes a plesiosaurus for up to 12 hours and can be ridden as a mount. Once it has been used, it can’t be used again until 4 days have passed.

While you are riding the plesiosaurus, you can use it to cast Water Breathing at will.