After we save Roland in A Dam Fine Rescue mission, we can return to Sir Hammerlock at Moxxi's bar in Sanctuary to get another optional mission from him, called Borderlands 2 Mighty Morphin'.
In Borderlands 2 Mighty Morphin', Sir Hammerlock tells us about a new type of enemy, the varkid, and that he wants us to go and inject these creatures with a special serum after they morphed.
"Sir Hammerlock would like you to find some varkids in Tundra Express, force them to morph, and then inject their cocoons with a special serum so he can study their morphing qualities. Be careful, though; a varkid won't morph if it is the last one alive, and you can only inject regular varkid pods. Badass pods won't work."
Experience: 2333 XP
The first thing that needs to be done is to take the evolutionary injector from Sir Hammerlock.
Next, we need to travel to Tundra Express using the new exit point from Three Horns Divide (if we haven't already visited the area). In this area, the varkids are everywhere, so it shouldn't be hard at all to find some.
Before injecting their pods, we have to make them morph, so for that to happen they need to be weakened.
Note: If a varkid is alone in an area, it will not morph.
A good strategy is to melee the smaller ones and then move back so they can transform into pods. Once we have a pod, we need to quickly get near it and press the action button to inject it with Sir Hammerlock's serum.
We must be aware that from the injected pod a mutated badass varkid will be spawned, that can easily take down our shields using corrosive attacks. We use a fire weapon on this creature, and then we collect a sample once the creature is dead. But the mission is far from over, because Sir Hammerlock needs four samples. So we apply the same strategy on the varkids we find, and after we collect all samples, we can return to Sir Hammerlock in Sanctuary and turn in Borderlands 2 Mighty Morphin' mission.
Tip: We shouldn't inject more than one pod a time, because one mutated badass varkid at a time is more than enough for our character.
As soon as we get our rewards, we can access more optional missions, in Tundra Express, including No Hard Feelings.