Glitch? Horn of Blasting is the only magical instrument that doesn't have "Spell Focus (Instrument)" preventing Bards from casting spells with M components. : r/CrownOfTheMagister
D&D 5e: Loxodon Race Guide - Sage Gamers
5E Mini-Dungeon #009: Tiikeri's Revenge -
Horn of Blasting - Magic Items - D&D Beyond
Amazon.com: Dungeons and Dragons Attack Wing: Frost Giant Expansion : Toys & Games