It's a level 7 clerical spell. I stuns all enemies in a huge radius for one round (if the cleric invokes the next word immediately afterwards, the enemies will just keep stunned)
Might not sound so impressing, but..
Stunned targets are automatically hit (good for power attack and to hit those"insane AC" monsters)
Targets get NO saving throw against holy word. Only good alignment monsters are immune to it, but tell me one monster with good alignment in IWD2 !
It's THE lifesaver. For example, the Barbarian is 20 yard away from the cleric, needs urgently a heal.. Until the cleric can reach him, he's dead three times already. So cleric casts holy word, all monsters are stunned.. Enough time for the cleric to walk there and cast a heal. (holy word and heal both have a casting time of 1.. that means, just after the barbarian is fully healed up, the monsters start moving again)
Chris
Where there's a will, there is a way.
And if there is no way, then we're going to hack and shoot it clear!