I dont know much about Avatar , but I love the way Fire Lord Zukos exile text plays with airbending, which seems like an intentional nod to his eventual partnership with Aang
It looks a bit too expensive to do much work in Limited, as the quality of cards you'll be able to buy back with it will be a lot lower than in Constructed
Not only is Shadowspear an excellent inclusion in any deck looking for answers to hexproof/indestructible, but it's basically an auto-include in Equipment decks, where outside of its function of a hate card it's also pretty much a strict upgrade to Loxodon Warhammer, a card I'm fond of
For example, if youre playing against a blue player, maybe name Rhystic Study and exile it before it ever makes it into their hand
One mechanic thats very popular in Politics decks (and Commander in general) is monarch
Try avoiding Rakdos and Gruul