Alright there was some talk about making this thread on the general discussion, and I figured I had some time to put down the BNBs I've figured out so far.
Regular Mode Confirms:
The combo you're going to want to look for mid-screen is a normal string into:
String -> 236B~214A 2A 5B 623B~214B 623B (+6 stocks)
The damage here varies based off of what you confirmed obviously, but whats important about this bnb is that it builds 6 Zero Weave Stocks. If you confirm off a 2A -> 5B -> 5C, you're going to get damage in the range of 1.7k. Comparatively, jC -> 5B -> 5C as your string nets about 2.8k damage.
In the corner the string confirm is much the same except make this substitution:
String -> 236B~214A 2A 5B 623B~214A 623B (+6 stocks)
If you use the B teleport in the corner to follow up Crusade Seraphim, you'll cross under the opponent. In this situation you're still able to reverse input the 623C Crusade Seraphim to finish the combo, but it seems unreliable(perhaps character specific? I've noted you don't need always need to reverse input, while other times you most certainly do).
The Relaunch Combos:
These combos all follow the basic route: (N Starter) > C move > 236B > 214A > launcher > air route > ender.
Launchers:
2B > 5C - Works on almost the entire cast at most ranges. Requires close range against Taokaka and Rachel. Does not work on Makoto.
2A > 5C - Works on all characters at most ranges. Requires close range against Taokaka and Makoto.
Air Route: (these are generally done from super jumping after a launcher)
j.BAC - Universally applicable. Works midscreen on everyone. Hardest timing. Works at further range than any other route. Only path that has been tested to work on Noel, and is obnoxiously hard on her.
j.BAAC - Slightly easier than j.BAC. Does not work on Makoto, Taokaka. Is prohibitively hard against Rachel (see j.ABAC for her). Hakumen, Valk, Bang, and a few others require no timing.
j.ABAC - Variation of j.BAAC for certain characters. Suggested against Carl and Rachel. Requires minimal timing effort. Also arguably useful for Litchi or other characters if BAAC is dropping, I guess. Not sure why I have Litchi listed as a "maybe" here, but whatever.
j.BABC - Easiest combo path. Only works on Relius, Bullet, Jin, Tsubaki, Platinum, Nu*, and Kokonoe. Requires literally no timing, just do all the hits as fast as possible.
*(Nu requires a 2A > 5C starter to use the j.BABC path)
Enders:
5A into blah into 623C > sj.C > j.D oki
5A -> 5C -> Another jump loop works off fatal counters such as 2C as the starter.
Gain Art Mode:
Combos in Gain Art mode vary a lot depending on how many resources you want to spend or have, so remember that if you run out of stocks half way, you may need to alter your confirm. A good example of this is the optional use of Phorizer after Strike Fall in combos. At maximum scaling phorizer still hits for 660 damage so any combo that ends and strike fall can have a phorizer at the end if you have the meter to spare.
Midscreen:
5B 5C 236C~6D~214B 5B 5C jC jC 236C~214D jC jC 236C~214D jC jC 236C~D optional Phorizer ender: 236236C (4013 without ender, 4673 with, uses 4 stocks)
623B~214D jC jC 236C~214D jC jC 236C~214D jC jC 236C~D optional Phorizer ender: 236236C (3091 without ender, 3751 with)
Corner:
5B 5C 236C~6D 2C 236B~214A 2A 5B 623B~214D jC jC 236C~214D jC jC 236C~D optional Phorizer ender: 236236C(4106 without ender, 4673 with, uses 4 stocks)
FC 3C 2C 623C~6D 2C 236B~214A 5C 623B~214D jC jC 236C~214D jC jC 236C~D optional Phorizer ender: 236236C(4849 without ender, 5509 with, Probably not optimal, but the best FC confirm I've come up with so far, potentially longer air combo could be done but the strike fall already needs to be canceled into immediately so that's questionable if you want that ender)
Comboing into Astral
CH 623C -> 632146C (works midscreen and corner)
5B 5C 236C~6D 632146C (Works midscreen and corner, easier in corner however. Overdrive also makes this easier due to reduced push back on Valkyrie Astraea)
5C -> Astral
Throw -> Astral
Air Throw -> Astral
EDIT: Combos from the thread thrown into the first post, I'm not sure what here is optimal, but these do at least all work, and for the most part they serve slightly different purposes.
Throw combos:
GA: Throw > CT > 5C > 236C~6D > 5C > j.B > j.C > j.B > j.C > 236C~D > 236236C - 4681 damage
Airthrow > 6C > j.C > jc.C > j.236C~D [2542 damage, 18 heat]
Regular: Throw > 236B~214A > 2B > 5B > 623B~214A > 623C [2828 damage, 20 heat, 6 stars]
Throw > 623B~214A > 623C > sj.B > jc.BC(~D) [2762 damage, ?? heat, 4 stars]
Throw > 214B > 5B > 5C > sj.BAB > jc.BC~D [2777 damage, 19 heat]
Regular mode combos:
5B > 5C > 236B~214A > 2A > 5C > SJC > j.B > j.A > j.A > j.C > 5A > 5C > 623B~214B > 623C (3000 Damage / +6 Stocks)
FC 2C > 6C > 236B-214A > 2B > 5C > sj.B > j.A > j.C > 5A > 5C > 623C > sj.B > j.A > j.C > j.236C
6 stars, 27 meter, 3834 dmg
FC 2C > 6C > 236B-214A > 2B > 5C > sj.B > j.A > j.C > 5A > 5C > sj.B > j.A > j.C > 5A > 5C > sj.B > j.A > j.C > j.236C
4 stars, 27 meter, 3866 dmg
AA CH 623C > 5B > 623B~214B > 623B [???? damage, ?? heat, 6 stars]
Gain Art combos:
(Corner) 5B > 236C~6D > 2C > 5C > 2C(1) > 623C > sj.C > dj.C > j.236C~D > 5A > 5C > 623B~D - 4449, 3 stars
CT > 2C > 236C~6D > 2C > OD > 5C > 2C(1) > 236B > 214A > 5C > 2C(1) > j.B > j.C > dj.B > j.C > j.236C~D > 236236C - 5652 damage
j.C > 2B > 5B > 236C~6D > 2C > 5C > 2C(1) > 236B~214A > 5C > 2C(1) > 6C > j.C > jc.C > j.236C~D [3764 damage, 27 heat]