https://www.theamazonbasin.com/wiki/index.php?title=Shadow_Mastereverything you need to know
it has 376*(1+0.15*(slvl-1)) life, 40% DR, and has rare claws of different base types depending on skill level with +15% enhanced damage per level from its +10 str/+10 dex. Skills are set to 1/2 sin's level + 1/3 sm skill level, rounded down for both, and add +1 for battle command
a level 22 shadow master has 1560 life, 77% all resists base, +330% ed, and spawns with 2x rare scissors suwayyah, rare helm, rare armor, 2x rare rings and rare ogre gauntlets. It will easily become immune to elements with fade active. It can get very, very high damage resistance with high level fade, but can't become quite physical immune since fade won't go high enough.
so for example, if a ghost has a level 45 venom / 45 shadow master and level 12 dragon claw after +skills, that SM will have its own +675% ed from stats, 2x, rare scissors suwayyah and level 22 dragon claw of its own (+155% ed / 565% ar- but since it cannot have claw mastery, no synergy). The damage depends on the rare claw rolls, but even if they spawn with just +50% enhanced damage on a mediocre roll, that's already ~630 physical damage when it pokes someone, and carries level 38 venom for 1000 poison damage over 0.4s
this is why ghosts can actually whittle people down quite effectively with just mind blast + sm alone without exposing themselves to counterattack, because those 300 damage mb and sm pokes add up fast