Here's the deal: Using Fiora's ult (Grand Challenge) is kinda off putting when you have the enemy who can go invis.
You don't get to pussy out when you're being challenged to a duel, which means no wussy Talon ults, no Rango ults, no Akali shrouds, etc.
You can wussy out if you're willing to Flash out or use various other spells to escape it but not invis.
1. Fiora's ult should give True Sight for it's duration to prevent abuse cases that invis provides. You don't get to piece out of it unless you're willing to spend more resources to do it.
2. I feel like extending it's duration to 10 seconds, should the opponent chose not to fight, he can't wait it out and rejoin that easily.
3. Since the ult has the **POTENTIAL** to deal damage, which means you might do 0, it's a really steep price to cast. I think you should reconsider halving the cost or make it free because Ekko had nice damage and utility built in from the start and he had a run with no cost at all. At least test it out on PBE to see if it jives well with her kit.
How do you feel about Juggernaut Fiora? She doesn't seem reliable as a glass AD cannon as the only thing protecting you from CC is Riposte that's on a lengthy CD.
I still think Riven, Irelia, Yasuo and Rengar are better than her because she really has some CDR and mana problems and if you die once or fall behind, your laning is gonna suck from that point on.
She is advertised as a 1v1 champion which means her teamfighting is atrocious, especially with no items.