Not sure if this has been discussed here before but Here it goes.
I accidenaly stumbled upon what I think is probably the easiest way to lvl up Krieg and whatever friend you might have in your party.
You need the following:
Slag betty. A crossfire or legendary bonny is preferable but not necessary.
Sickle classmod.
The mission ‘Mighty morphin’
Go to tundra express farmhouse, run circles around it to wake up as many varkids as possible, inject ALL the pods you can and throw as many grenades as you can.
Once you slip below 30% health release the beast and go find a small unevolved Varkid to set of the bloodsplosion.
Each mutated varkid gives something like 5.8k exp, and you can get around 5-6 each run. It is fast, it is fun, and as long as you don’t pick up the Mighty morphin mission items you can keep doing it as long as you want.
Only Krieg can do this trick. The entire point of it is that it is faster then the alternatives.
Sure the other characters can kill mutated varkids for the same amount of exp, but it would be faster to kill master gee’s worms, or just kill the snowman.
Krieg can bloodsplode everything and get a handfull (5-10) mutants in each bloodsplosion, and he can do it really fast. It is by far the easiest place to lvl up as Krieg imo.