I wouldnt say that. Sure she is perfect for the Nilgal fight being a knight with a cleanse and dual attacks for more damage. But there are other heroes that would be great for it that I dont have. Someone with a reliable attack down for starters and a good single target damage dealer than can do more than my Tenebria. Vivian is actually more useful than Lilias imo because of her three turn immunity. And the fight is certainly doable with other knights.