When can I bend?

In order to be balanced, some limitations are required to determine when you can and can't bend your particular elements. Treating every moment in a piece of media as canon that you can mimic in game can pose some problems.

For example, King Bumi earthbending when inside of what is essentially a coffin when only his head is exposed. Allowing that kind of power while completely restrained can create problems.

In general, I'd say that anything that can prevent you from making unarmed attacks can also prevent you from using elemental blast/wave/techniques. Some exceptions can be made (like firebending's melt feature), but in general, standard methods of restraint should be sufficient to prevent most abilities from functioning.

Elemental Jank

In the show, elemental attacks can originate from places other than directly where the attacker is standing.

I have simplified elemental blast to always be ranged from a range, and letting you choose to make it ranged or melee when creatures are within your natural reach. Most abilities require you, or a spot near you, as the origin point.