The Boss Rush mode is unlocked after finishing main story twice , once while recruiting with Zangetsu all 3 helpers and granting ya Those Left Behind achievement and the other, finishing it while killing em all with Zangetsu and granting ya Emperor of Darkness Those can be done either or casual or veteran.

The Boss Rush mode has to be done in a single sitting (no saves/continues/lives).
It's in Veteran difficulty , so the knockback on hit effect applies and bosses last stand Joooooooojo attack can kill you.


You have all the power ups and members unlocked from start/1st boss
BUT
each time you take a power up it will be applied only for your next boss engagment and no furthermore.
There are 2 big Hearts for HP but they re for a single use (they dont refresh after u beat a boss) and for the entire run so pick em wisely.
If you lose health you ll have to continue to the next boss with remaining HP while if one of your members die, you ll have to go through the same boss from beginning (just like in story mode)
Its advised that if you lose a crucial member, to just exit the mode and restart (since there is no reviving) unless you wanna go for the challenge with your remaining ones.

So 1st-3rd boss , i use no power ups.
Miriam (for me) is the most useful member since she can hit 1st boss from afar ,fast engage and hit 2nd boss on 1st phase and has better jumping for the coin platforming on the 3rd one .

For the 4rth boss i think the fastest way to do is like i did (watch vid)
MIriam's Axe 2 shots first dragon , while for last dragon head it needs 3 axe swings and 2 basic attacks.

For the 5th boss use Gebel for hitting it while aerial and swap to Miriam for destroying pillars and down + A for the wind pushover attack of the boss.
If the boss goes for the diagonal attack sequence simply jump above him to the other side.

For the 6th boss , Gebel once again makes the fight pretty trivial with his upward attack , a cheese method is also using Alfred's Auto tracking lighting balls or whatever that is and she ll be done in a few seconds with it.

I find 7th one rather easy , its just timed platforming, there is nothing troubling about it , just duck his laser & avoid the red marked platforms.

Now for the 8th and last boss. Here i died quite a few times.

Alfred's Fire Vest that negates attack is a must for both phases (As you can see in vid it nullifies the aoe dust attack and you can stay safe even inside)
Zangetsu's double damage/fire aura help quite a bit in finishing the 1st phase fast without consuming all your MP.
For Miriam i take the upward knifes for 2nd phase mostly
As for Gebel he has the best attack for the crescent moons on the last phase but you can play it safe with Alfred Fire Circle.

That's it !!
Well Done ya vampire loves!!!

If you wanna do it in a easier way.

Hold down one of the following buttons and then press start on boss rush:

I - Nightmare Mode Boss Difficulty.
N - Ultimate Zangetsu (Normal Boss Difficulty).
T - Infinite Weapon Points.
C - Subweapons and Hearts Regenerate after each Battle.

Note that i didnt use none of those on my full clear vid/run .
Only because i found out about them afterwards ( ͡° ͜ʖ ͡°)