Let's breakdown combat system.
Game is built around charging. When you press attack button the gauge under healthbar starts filling up and you see circles on the ground, when you release the button you get powered up attack. There is also "perfect charge" mechanic that does something you release button just at the right time (entire screen flashes with colour of the element), but i am not sure what it does...
The gauge stay up for a while after charged attack and during that time your attack will be boosted. That's why it's useful to do one charge attack to fill the gauge before every encounter.
For defence you have dodging and guarding. Dodging is standard stuff: it is invincible during the dodge so you can dodge into the attack and as long as you exit the animation in the safe zone you're fine. There is a cooldown after 5 consecutive dodges to prevent you from spamming it too much.
Guarding is basically
Royal Guard from DMC3/4. You can compare it to Mahaa-Kalaa from Bayonetta or parrying from MGR, but here you don't need any directional input -- you just press left trigger with the right timing to counter an attack.
Guarding is kinda overpowered, so you will be tempted not to do anything and lure out enemies to attack so you can counter them and one hit kill them.
Triple triad members can guard as well and if you try to attack them during that state you will initiate God of War style QTE where you need to press directions with a left stick.
There is also stun mechanic, if you hit an enemy hard enough he gets dizzy and will be open for finishing move with B. You're invincible during finishing move animation and this move also hits everyone in the area so it's a life saver against big crowds.
Waterbending:
Long range stuff. It has cool unlockable water whip move -- you throw a water sprout and pull an enemy towards you. It's very cool to send an enemy flying and immeditately pull him back with it. There is also freezing attack but i've yet to freeze anyone with it.
Earthbending:
The most fun of all bending arts. It's extremely satisfying to hit enemies with charging hits with it. All attacks have area of effect and are VERY powerful. Earthbending also has the best combos right of the gate: simple XXX is very good, XXY -- is even better, YY is great and Y in the air is AMAZING (even moreso if charged). You hang in the air and then fall down to the ground and causing huge columns of earth to come out:
Firebending:
Kinda eh. Weak, nothing special. Fire kick move look pretty cool, but it's not super useful because it concentrates fire on only one enemy:
I've unlocked a few more moves for it so it might get more useful later on. We'll see.
Airbending:
I've just unlocked it, so it didn't have too much time. But it felt VERY good, if a little overpowered, i was just mashing buttons and enemies were literally flying all over the place:
Game overall gets very challenging, both in combat and in other parts. You can cheese combat parts a bit by abusing finishing moves invinciblity and using camera trick where you focus the camera on one enemy because by the unwritten rule of all action games offscreen enemies become docile.
There is one particular temple run style sequence where i spent 20 minutes trying to beat it:
^ very, very hard.