I could be dead wrong, but the more I consider the related scriptures, the more I think that the false Christ's working miracles in the last days are not individuals pretending to be the promised Messiah, but are instead the miracles of the scientific and engineering community which cause people to give heed to whatever they say.
There are a number of scriptures condemning people for ignoring the miracles done in the scriptures:
John 14:10 Believest thou not that I am in the Father, and the Father in me? the words that I speak unto you I speak not of myself: but the Father that dwelleth in me, he doeth the works.
11 Believe me that I am in the Father, and the Father in me: or else believe me for the very works’ sake.
We also read
Matt 11:21 Woe unto thee, Chorazin! woe unto thee, Bethsaida! for if the mighty works, which were done in you, had been done in Tyre and Sidon, they would have repented long ago in sackcloth and ashes.
In the Book of Mormon people cease to be impressed by a work or a miracle We also read there:
3 Nephi 8:1 And now it came to pass that according to our record, and we know our record to be true, for behold, it was a just man who did keep the record—for he truly did many miracles in the name of Jesus; and there was not any man who could do a miracle in the name of Jesus save he were cleansed every whit from his iniquity—.
So I don't believe that the false christ's working miracles in the last days refer to miracles in the usual sense. I am strongly suspicious they refer to the technological and medical miracles we see all around us, and the credibility those "miracles" give to other, completely bogus claims of science. Evolution would be an obvious first false teaching that people buy into.
Consider a recent example. At some point there is a claim there was a study "proving" that people were born gay. Now if that happened 100 years ago everyone would have laughed at whatever group had made the study and ignored it except to retell as a joke. But now, because it is a "study" and all studies have great credence in people's minds for no better reason than the fact that they are impressed by their many modern miracles, people buy into whatever they say.