I made a horde monster for Into the Heart of the Dragon that becomes a bigger horde as the players use more Exploratory Surgery
Bone Spurs
Large, Horde
Shards of Bone (1d6+3, 1 Piercing) HP 7, Armor 3
Special Qualities Weak to Acid
A collection of random bone shards from the dragon or from Something it has eaten.
Instinct: To defend the territory the dragon has assigned it to.
Swarm them
Latch on
Crack their Armor
It uses house rules from this blog post: https://steelsmiter.blogspot.com/2016/08/on-subject-of-hordes-and-mass-combat-in.html