Shroud and the constant Debuff + spell denial is incredible. The combination of being very difficult to target or kill plus providing multiple kinds of passive AoE protection is great. Plus, she is a fine combatant on her own, and can handle a 1-1 in a font -- though not, admittedly, with a champion of her cost, if you are running the Shroud build.
By spell denial, which spells are you referring to that are problematic to Fw? Basically there are no single target spells that I can think of which are a problem aside from reforge and shatter. She can help curb the effects of some aoe, which is fair, and maybe sometimes stop a reverberating blast. In all honesty though, is her spell denial an actual selling point, I see it mainly as a cost I don't need. That could be because I don't know every spell in the game, but I actually know a fair amount now. I've used her pretty extensively. I think I'll try and give her another whirl. She definetly is hard to judge, especially since I mainly used her in witches where she might be a bit weaker. She is more of an early game champion, from what I understand. Maybe BCA should just be God tier. Hard to compare any support to him really. Which is really due to ritual spells being so strong, and his design in general.
I think the spell denial can be very powerful. Also note that it stops things like Hammer Strike on her or friendly champions, and also prevents protective spells from being cast on nearby enemies. I would also, tentatively, agree that she is stronger outside of Witches, oddly enough. Yes, it means that you can't take both Shroud and Revel (because of no Witching Hour), but her AoE debuff doesn't matter when you already expect to curse most enemy champions.
Oh, that's why...i forgot revel gives her a free curse heal...i only u used her in witches lol. Witching hour is necessary in witches for sure