Brainstorming Onox's true form.

Onox's anthro form is actually a weakened form he assumes when he doesn't need to use his stronger forms, his true form is that of a massive western dragon (much like WoW's), and he has the ability to transform into various forms of dragonkin -- much like Ryu from the Breath of Fire series or a Manakete/Mamkute from Fire Emblem. However his true form isn't very efficient at spellcasting -- this is important to him since he likes to demonstrate his mastery of might and magic to others (he has the dark overlord archtype so he's an adept fighter AND spellcaster). His true form is too bulky to properly interact with smaller races, and ultimately tends to be 'overkill' for most day to day situations.

When he needs to, he shifts into his 3 most common forms which are a western form, an eastern form, and a wyvern form. His abilities and traits change with them, so he will use them to adapt to situations in a pinch. There are even more forms beyond that the big three, but they are usually much more niche.

TL;DR This is a concept for his true form, but he's usually in his anthro form because it's more mana efficient, he doesn't need as much food, and it let's him fight 'optimally'.