Well, congratulations Loony! It was up to the community to decide the tie breaker, and it appears you have won! You were able to gain 5 more votes than your competitor. Good work everybody! Excited to see these other 2 submissions in the contest summary we'll get!
Unless you can direct me the server to where I can test them (I won't bother creating one for myself for only testing sakes), for now I would vote for Spiritual Projection based on both descriptions of theirs from these thread.
Since I'm no techno/code whiz, I will only be judging by their in-games concept/features.
Generally I despise MultiAbilities, but I can excuse this because it adds more creative. Therefor I'm giving slight edge to @Loony's over @Brainwave's.
Although, that isn't the end and I can see flaws that are important to address. Starting with the canon argument, and yes, it might be good excuse that "not everthing has to be canon", which in these common-days addon developers tend to ignore as a guideline, but I still feel there could been a better execution on that part. Even If the spiritual projection in reality doesn't much offer and isn't explored to us much, due to the show storylines vague inspiration on that sub-technique, I still do feel something better could have replaced AstralAttack and SpiritualDrain, that would been more logical and not fluff.
For example, considering that airbenders that weild SpiritualProjection are obviously are more spiritual, this could have introduce an ability that summon spirits (like upsidedown rainbow sheep or enderman, which to me personally remind me more as spirits) that air to protect you (enderman teleporting you away, while sheep spawns WoolBlockade) and alike stuff from the show. Whilst it isn't directly related to Spirititual Projection, it would have been a nice easter egg about airbenders (aka only Jinora) that were highly in tute with spirits and all that spiritual mumbo-jumbo and being the user of this ability .
I have nothing else to add, apart that AstralAttack tends to give Oh-another-offensive-ability-for-pasifists (disapointment) vibe. Drain doesn't even make sense (how does spiritually fuel and keep bending active?)
Not sure If this was allowed in the contest, but I would have preffer If this was to replace initial ability by keeping stock's name +"EarthTunnel". Usually, servers happen to be suffering "must-have-2-many-over-dose-abilities-in-da-arsenal sydrome", which is the words that I recall somebody something putting them more better than I could word it. It might be a disgrace If I were to used an example with another addon, but for the argument excuse: I don't like having earthblast and earthline be seperate abilities when they could better off be overriding either either one of the other.
IMO, this ability is op, because you can collect blocks easily (If it happens to treat all blocks equally based on theory from reading its description).
Also, I find it more rip-off, which isn't any better but more impotent than the stock variation. For defensive usage, it's pretty pointless, because it would take figuratively hours and longer to dig a tunnel and enclosing it to the very depths where you could feel safe|secured|hidden from others. Same goes for utility/mining usage and I would probably more willing to spare my time and use all resources to craft a pickaxe, as I think my finger/ or hand would overtime become sore while using this ability due to the requirement of press&holding sneak key, rather inficently holding LMB. I just don't wanna strain my finger over a keyboard button when it removes only ONE block at a time.