The Barbarian invasion addon is not required to play this, all you need is a clean RTW install, and the version 1.2 patch.
To take out the elephaunts, i guess you require lots of archers with fire arrows, dunno though, i haven't gotten to installing the mod yet. But in Battle for Middle Earth, i made short work of those beasts with Rangers with flaming arrows, so i hope they didn't forget to add Rangers in this particular game as well. If you have to fight them with only infantry, or even cavalry, i DO know that you have your work cut out for yourself, these creatures ravage entire batallions in only a few seconds.
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