[Arch-vile]

Definitely intended Aang to be forced to switch up the elements. Going for Book 3ish Aang, where he can use all four elements with some skill. Aang did make peace with fire when he trained with the dragons in that season.

I'm not a huge fan of forcing him to use Air as one of the elements (I feel like it takes away a lot of the fun mix-and-match of the design), but we could go with something like this. I'd allow him to use Air second, otherwise he'd not be able to blow enemies away 4 spaces on the first attack without sending the enemy out of range.

AVATAR BENDING SPECIAL ATTACK
Range 4. Attack 4.
Before attacking, choose one of the following effects. You may not choose an effect more than once per turn.
• Air: After attacking, move the defending figure up to 4 spaces, during which it does not take leaving engagement attacks.
• Water: The defending figure subtracts 1 from its Defense and Move until the start of your next player turn.
• Earth: Add 2 to Aang’s Defense until the start of your next player turn.
• Fire: After inflicting one or more wounds, roll an unblockable attack die against the defending figure unless it has the Lava Resistant special power.
After attacking with this special attack, you may attack with this special attack one additional time, and you must choose Air if you did not choose Air for the first attack. Once per game, you may attack with this special attack four times in a turn.

Another option is to boost the attack of his Air special by 1, to show proficiency there. Then change Fire a bit so it's still got a use next to the buffed Air special.

AVATAR BENDING SPECIAL ATTACK
Range 4. Attack 4 + Special.
Before attacking, choose one of the following effects. You may not choose an effect more than once per turn.
• Air: Roll 1 additional attack die. After attacking, move the defending figure up to 4 spaces, during which it does not take leaving engagement attacks.
• Water: The defending figure subtracts 1 from its Defense and Move until the start of your next player turn.
• Earth: Add 2 to Aang’s Defense until the start of your next player turn.
• Fire: Instead of attacking, roll an unblockable attack die against the defending figure unless it has the Lava Resistant special power.
After attacking with this special attack, you may attack with this special attack one additional time. Once per game, you may attack with this special attack four times in a turn.

Also thought of another way to power up Air, and it would let us ditch Stealth Flying:

• Air: After attacking, move the defending figure and Aang up to 4 spaces each, during which they do not take leaving engagement attacks.

Overall I think I'd prefer to power up the Air special rather than force Air as an option. It would allow for more choices during gameplay.