Despite the smoke obscuring their vision, both Isabella and Cedric's senses were sharp enough to see through it so this didn't impede them at all.
For what's worth, Isabella was doing her best. She was already aware of the gap between him and Cedric, and she also knows that there is a high chance that she will lose here, but she didn't want this to be an easy win for Cedric, she'd be damned if she didn't make him work for it.
'Frozen Cloud!' She exclaimed inwardly, casting another spell that thickened the fog around the arena even more.
This spell was harmless for the most part. Its only effect is that it lowers the temperature of her surroundings quickly. That said, the low temperature makes it easier for her to cast her other spells so in a sense, Frozen Cloud could be considered as a support spell as well.
'Glacial Spear' was the next spell she used. She poured a lot of her mana into this spell, increasing its lethality overall.