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Nope, It's not still implied. For cards like Stronghold in the Desert, Evil Spawn (Gold) and Jephtah, if you hit a lost soul, it stays discarded.Of course there are counters to this strategy - Crumbs from the Masters Table can get a lost soul back, The Thankful Leper can always search them all out, I think there are one or two enhancements that can get them back. And in order to actually make it work you have to hit 2 souls, 3 if they stop burial with Lampstand, more if they have cards like TAS or Malchus.