I think it's oath rw in d2r . This is personally the coolest rune word for me. It has great properties. Originally "Oath" is a rune word meant for ladders only, but in Diablo 2 Resurrected it can also be put into sockets without ladders after Patch 2.4. The rune word was introduced when Diablo 2: Lord of Destruction was released.
Diablo II offers a variety of rune words that players can create by inserting specific combinations of runes into socketed items. The coolest rune word can be subjective and depend on a player's playstyle and preferences.