Pretty self-explanatory;
In this guide I will post the location and everything needed to start secret boss battles!

This first boss is a gigantic Kragg.

He can be found in the first "real" area of the game, Serenity's Waste.


Right there.


Now, to get there you can:

A) just go through the lava

B) take an alternative path.

Going on the alternative path:

Turn right as soon as you get out of Springs' base, turn right and climb the ledge. You will be facing a pipe:



Climb this ledge and go beyond the pipe.
Now climb the ledge to your left:


From this ledge you can access the boss area, just jump down to this platform:



And from there, jump to the small platform next to the lava:


This is the entrance to the boss battle:


In the end of this hallway, you will have to drop down:


As soon as you land, the boss will spawn:


He is level 30 in the first playthrough and 52 in TVHM.

His drops usually consist in purples, money, whites/greens and a lot of moonstones.

He also has a chance to trop the legendary rocket launcher "The Thingy" - no picture available as Iwajira hates me and didn't drop it a single time for me :'(

Yes, Nel, the guy whom the dead soldier asks you to call a d*ck, is in fact a secret boss!

Now, this guy is indeed a D*CK.
To get the fight you have to...well... Call him a D*ck again.
Here's the tricky part:
To insult him again, you need 2 pieces of some sort of billboard. One with a D and one with a K.

These are found on top of 2 buildings, one of them is kinda hard to climb and the other one you need to grenade jump your way to the top.

This is the first building:




Use the geyser to jump up:


After you're up there, move forward and turn right.
This will be (in my opinion) the hardest jump you'll have to make... Jump on top of this structure:


It might take a bit of a twist jumping to get there and you WILL NEED the boost from OZ kit.

After you make it, jump to this one directly in front of you:


Turn 180º and jump up here:


Just jump up and look around the top of the building for the first part:




Onto the second building, directly in front of where you first meet Nel:


Get on top of it using the geyser-thing and go around until you find the chest. Once there, jump to the structure behind the chest:


Then 180º turn and boost jump here:


After you 180º again, you'll jump on a structure and...

Here comes the first nade-jump.
You have to jump and go right so you land here:


After you make it, you nade-jump once more to the top of the building:




NOTE: YOU DONT NEED TO NADE-JUMP, CHECK VIDEO SECTION FOR MORE INFO.

Look around for the second part of the billboard:


After you get it, jump down facing the bridge where Nel is, turn back to the building and place the parts:


You will hear Nel getting pissed of at you:


He will run to the location of the first building and call his homies:



They will scale to the max level of the playthrough you're in (30 on first, 50 on TVHM)

Nel has a chance to drop the Skullmasher:







NOTE: Apologies for the "bad" screenshots, paint screwd me over. If needed I will reupload them, but I believe they are enough of an explanation (if you feel like they should be change please leave a comment down below ;-; )

NOTE2: The map is Regolith Range, you can access it through Serenity's waste

IWAJIRA:






NEL:

Props to:
Zovea
Space-Lord MonkeyScience
Electric-Stinger

for giving me the tip on not needing to nade-jump on this one! AKA Method 2.
It is included in this video but not in the writen guide at the moment!

I am still trying to find new secret bosses.

Whenever I find one, I will post it here.

I believe there are more, since there aren't that many repeatable bosses on the first playthrough to farm. Also both of the begining areas have a secret one... so who knows, maybe there are more, maybe there aren't...

Soon I will also be uploading video-guides of these fights on youtube, you can check them out on my channel here .