Yes if you are really low on clintz I would sell them. Nobody uses Bangers in elo because they are so weak now. To be competitive you would at least need to have Blaaster and Vermyn N, and that will cost you over 100,000 clintz. Their best 5* Shann and Beeboy are both elo banned.
If you really like Bangers and are set on using them, you could always use them in a half deck with something else I guess.
Blaaster Cr barely usable? That is just false. Bangers used to be the most powerful clan in the game and big reason was because Blaaster was one of the best 4* in the game. He isn't quite as good anymore because new cards are so powerful. He is still a Bangers staple and price with keep rising because of iconic status.
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