get something specific among these 4, and use it as a key. once done, decode using the key
nslvarftdiigmfgwgzisklvficndyextbwdwjgbxendewtv klrgqmprslvqamirwxfv
STEP 1 HINT: how "massive"
STEP 2 HINT: think outside your box

final-ans: [key used for decoding the string][the actual answer]

puzzle by nat (@trin2trotoluene)