Variant heroes and villains are unlocked by accomplishing secret storyline-based challenges. You can come across them during normal play by exploring different play styles, or by actively seeking them out. Whenever new variants have been made available, the fan community has come together to discover the unlock conditions in a collaborative effort. We encourage you to join in the fun on our forums, the GTG forums, Steam community, or anywhere else!
Approximately 30 days after a Variant becomes available, or once the official unlock condition has been discovered (whichever happens first), we make it freely unlockable using a button. Press the Variants banner on a card, then the lock icon, and you will be able to unlock the variant without accomplishing the challenge. The challenge and associated achievement will still be available, so if you do perform it later, you'll get the unlock screen then. If you are stuck and want to find out the unlock conditions for a variant, visit the Variant Files page and take a look.