She had not been an Auror for this long without being able to handle a spell or two, and she deflected his spells without too much trouble. The shield from Severus helped, the spells bouncing off her in the direction of the man, hitting him even as he moved. The ropes she dispelled with a waive of her wand before casting off a strong stunning spell in his direction.
She could use stronger spells than that, but the battle scene was a mess, and if he moved she could hit one of her own, or a bystander, she would not risk that.
She followed up with more hexes, each stronger than the next, knowing that she had power to put behind relatively standards spells aimed to stop, capture or immobilise.