The Hooked Shortspear can be found in Out of the Abyss, page 224.
You gain a +1 bonus to attack rolls and damage rolls made with this magic weapon.
The weapon deals an extra 3d6 damage of the weapon's type if the target is a Dragon.
On a hit with this weapon, the wielder can forgo dealing damage and attempt to trip the target, in which case the target must succeed on a Strength saving throw or fall prone. The DC is 8 + the wielder's Strength modifier + the wielder's proficiency bonus.
A light weapon is small and easy to handle, making it ideal for use when fighting with two weapons.