I remember do research(aka googling for answers) about this, and kept coming to the same conclusion, that Prevent Monster Heal doesn't apply on Mercs. So either every popular answer that google showed
Prevent Monster Heal vs Travincal? • diablo2.io
First self-found Anni. Have javelin because merc was too weak, so used Hwanin's belt+throwing jav to prevent monster heal while kiting with blizzard, lower resist wand on switch. : r/diablo2
Diablo 2: Resurrected PC 💥 NL Softcore D2R 💥 Rune word Grief + Wpn Choice | eBay
Wooffftaaa. Dclone spawned in my game on my trash tier sorc. Had no prevent monster heal besides Nature's Peace randomly. So after many many attempts to melee Dclone with 75 Attack Rating,