Your ideas definitely fit with the fever-dream logic that Juice Galaxy is largely inspired by. I give you credit.
That being said, in my opinion, wearing somebody's head as a helmet/hat is a unique concept and one that shouldn't be prescribed to many characters. That goes double if the idea was to have them all talk; I for one like the Wawsp Queen's head's trait of talking while she's worn, being her own trait. It helps her stand out as a unique character- which is definitely needed in light of her fairly generic bad-guy monologue upon first being met.
This means that if we get any more wearable heads, they should be dead. To this condition I say absolutely not to Ingot's head being wearable.
I admit I'm biased about this too. I for one rather like Ingot as a character in Juice Galaxy; he's one of the only friendly faces in a world full of creatures who otherwise either barely care you exist or are outright eager to harm you. Incapacitating (I refuse to call it 'killing') him in the current game is bad enough; the idea of wearing his head wretches my gut.
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The idea of a Dragin Queen or King is intriguing. I personally though, would only want that if the Dragin King/Queen had a design that combined the goofy Dragin we know with something genuinely formidable and imposing; perhaps simply a scaled-up Dragin with proper wings and a tail, with a crown worn crookedly; and the ability to fly at high speeds and breathe flame against the player (a la recently-added fire attacks/damage, turned against us) as well as to just ram us.
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My favorite idea of yours is your "Disguisers" idea. Right now, in my opinion, there is far too much convenient loot in Juice Galaxy. Spawn rates are so high that, topped onto the various weapons just lying around for us to take already, weapons and cosmetics, including more powerful ones, just don't feel rewarding to grab.
Your idea could really help give some much-needed mix-up to the empty looting in this game. This, especially if these Disguisers strongly preferred to disguise as higher-level and "unique" weapons and cosmetics, such as the Draginslayer and the new Wawsp weapons, and if they strongly favor randomly-dropped weapons, leaving "earned" weapons (such as the Draginslayer from Mrs. Slithers, as opposed to just out of any old crate).
I'd like to also suggest that the Disguisers' levels benefit from the weapons' own size and/or our distance into the wilderness.