*Normally, the crushers near the end of the level are meant to kill the two Arch-viles to achieve 100% kills. Unfortunately, the D44D mod's second-wind mechanic for demons means the Arch-viles will always recover before being killed.
In short, the Arch-viles cannot be killed. At all.
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Grab Doom 4 for Doom (and any other compatible resource packs you'd like) here: https://forum.zdoom.org/viewtopic.php?f=19&t=54843&p=967174#p967174
Also, you'll need a legit copy of your PLUTONIA.WAD file, either from a copy of your own discs, or from a digital distributor (I purchased & downloaded my copy of Final Doom through GoG).
Add D44D, GZDoom, any other resource packs you've downloaded & your WAD to the same directory, double click D4D DragAndDrop to start the launcher, and you should be good to go! Have a blast!