The common Boneclang has a slight pink tint to its bones and wears a gold breastplate. They have two hit points and can attack with a simple swipe that does one full health bubble of damage. On death they drop their skull. The skulls can be hit by the player, causing them to break, but can also be used to damage enemies. Their heads and bodies can often be found unattached.
Boneclang Honchos are identical to the common Boneclangs, except for the giant crown they wear. On death their skull retains the crown and cannot be destroyed. Importantly, this still weighs down the skeleton platforms. They only appear in the Lich Yard. The player must be cautious, because the big skull head might cause the platform to sink, leading to the deadly water unique to the Lich Yard. Also, when the player takes away the skull head, the skeleton platforms will raise all the way up and will potentially crush the player. However, the player can lower the platform by jumping up. These skulls also crush enemies in one hit. They don’t appear in Specter of Torment.
The Loose Boneclang is solid white with red armor. When first struck, its skull detaches, rendering the Boneclang blind. In this state, it will simply walk forward until it reaches a ledge or collides with something solid, prompting it to turn and walk in the other direction. They only appear in the Lich Yard.
Brittle Boneclangs have a notable green tinge and wear grey armor. What sets them apart from the other Boneclangs is that they only possess one hit point. Notably, Specter Knight can summon three of them to aid him. They appear notably in the Lich Yard and Tower of Fate: Ascent. One also appears near the end of the Plains in Specter of Torment.
Moreover, in Specter of Torment Specter Knight can summon a Brittle Boneclang with the upgraded Skeletal Sentry, which stands still and fires flame arrows in the direction Specter Knight faces.
One of the Joustus cards in King of Cards is a Boneclang Honcho card which can push other cards to the left using its Double Arrow. It's also a Slam card, which means it will automatically try to push all adjacent cards when first placed on the board.
The model for Boneclangs in the game's files is simply named "Skeleton".
Notably the Boneclang that appear at the banquet after beating the Plains is the only minion recruit that will continue to donate money to Specter Knight even after their first conversation, albeit only once for each visit of the Tower of Fate hub. Though instead of three pink gems worth 200 gold each, it's just one gem worth 1 gold.