According to a leak from Pokemon Go Twitter sleuth Chrales, Niantic's catch-'em-up is adding three new type-specific Pokemon lures. It's unclear when these lures will arrive - and Niantic has yet to confirm their existence at all - but if the leak is right, Glacial, Magnetic, and Mossy lures are on the way.
Pokemon Go has always had consumable lures which attract more and rarer Pokemon, but these three lures will reportedly differ by focusing on very specific Pokemon. Per Chrales' tweet, Glacial lures will be especially effective for Pokemon "that love the cold," Magnetic lures will appeal to Pokemon "that possess a magnetic field," and Mossy lures will bring all the Pokemon "that love mossy scents" to the yard.
Even with these descriptions, It's not entirely clear which Pokemon these lures will affect. When I first heard of the Magnetic lure, I figured it would affect all Thunder-type Pokemon, but I suppose not all of them have a magnetic field. Are we talking Magnemite, Magneton, and other magnet-themed Pokemon here, or am I just reading too much into this? Likewise, will the Glacial lure only work on Ice-type Pokemon, or maybe some Ice-Water hybrids like Lapras? Then there's the Mossy lure, which could conceivably affect Grass, Bug, or Ground types.
All of these lures can also reportedly cause Pokemon to evolve, which could mean they'll cause more evolved Pokemon to appear, but there's no telling how they'll factor in. If I pop a Glacial lure in the middle of a herd of Eevee, would they all evolve into Glaceon? Glaceon is currently unavailable in Pokemon Go, but many fans reckon these lures could unlock it, along with a few other absentees like Leafeon and Magnezone. In the same vein, could I use these lures to evolve Pokemon I've already caught? Probably not, but until we get official word from Niantic, we can only speculate.
While we wait on these new lures, you've still got a few days left on the Pokemon Go Detective Pikachu event.