OK, just seen the episode and I must say it bcomes clear more and more.

1st. on Korra and Co.

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WEll, indeed she never heard of chiblockers before (well, maybe from stories like Katara's and Kyoshi warriors, but it's not a real know technique. She also exacted surprise when she lost her bending liek WHAT FOUL CORCERY IS THIS!, but with an inner voice. Mako ofcourse educated her and she hasn't really fought them since. Scond, IN battle fire is the easiest to use and to adapt to. You create your won element and you can change (of the fire, water and earth bending styles) direction easiest. This will change ofcourse when she masters airbending. Then whe will be able to pwn those chi blockers since you can't block chi to people at your back.


on lightning
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Lightning is still rare. Indees mentioned the gangleader uses it in his name. Iroh explained lightningbending as beïng the purest form of fire bending in existence. You literally generate heat so pure it becomes lightning instead of fire. Also, in the factory we can only see a handful of them and it is known that bending has had quite the lift in power and knowledge abou tit since republic city has been formed. IN probending it is quite useless becuase 1) generating the lightning takes a lot of time and take a lot of stamina. Bolin explained that the dynamic nature of probending requires the earthbender to adopt a far more dynamic style, "Else you are a sitting turtleduck".


Last but not least, Amon:
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2 options present themselves to me: 1) Amon can actually really spiritbend and control his spiritbending to avoid teh flashy effects, and make the diminishing more gradual instead of just flipping the switch, or, 2) (most likely) it's indeed and advanced form of chi blocking. The reason i choose 2 above 1 is simple: IN the end of TLAB, ang faced the firelord head on and used the head and heartchakras to take away his bending (like the lionturtle did). Amon uses only 1 hand and faces the enemies back. (important detail) he lays his one hand on the head, and the other at the back (to disable the chakra azula struck too). the scene went liek this: bolt attacked with lightning, Amon grabbedthe arm, guided it, pinned it with chiblicking disallowing for arm movement, letting the element run free, and pressurize back and head to shut off the bending like one would close a watertap. That and I guess flashing lights is a prominent feature of spiritbending like we saw with Aang the lionturtle and Ozai.

The real question is: how does Amon access the spiritworld? IN TLAB we were told only the Avatar could enter the spiritworld and communicate with the spirits. This reeks of asspull...