101Leafy researched the games.
Khezu Horn+

Made to look like the mouth of a dreadful Khezu. Shape and tone are unforgettable.
| Class | Hunting Horn |
|---|---|
| Rarity | 4 |
| Attack | 780 |
| Thunder | 290 |
| Slots | 1 |
| Price | 5,040z |
Upgrades
| Upgraded from | Khezu Horn |
|---|---|
| Upgrades into | Purse Bop, Khezu Flute, Blood Horn |
Upgrade tree from モンスターハンターポータブル 2nd G 公式ガイドブック (Enterbrain, 2008), page 738.