Instead, they equip it to their mercenary in order to benefit from its Meditation aura, which greatly boosts the player’s own mana regeneration. The Insight runeword, for polearms or staves, is one of the most overpowered of all, but most players don’t wield it themselves.
The best runewords in Diablo 2: Resurrected are, let’s be honest, the really overpowered ones.