I am not sure they can go retroactive with a punitive tax. I think they can only go retroactive on an easing situation. Could be wrong on that and I wouldn't put it pass this bunch.
Thus, the "tries" part of the question.
It'd IMMEDIATELY get litigated, but I'm fairly certain that the lame duck session (esp. if the demoncraps lose control of the House and their 60 in the Senate) will push it.