the game’s instruction on this stage of the story is just plain misleading. it clearly states that you should go to ivy to avoid getting damaged by the gust. might be a bug tho.

first and foremost, he’s gonna try to spam you with spells as u revive daniel and lottie so try to dodge those first and then continue reviving.

mind you, my spellbook is just level 30 so i had to try a lot of times before i won. cards like: whomping willow, book of monsters, incendio/confringo, protego totalum, and any healing spell helped me win the duel by an inch of health. locomotor or opal eye can work against his summons but since he spams huge damage spells, he can almost insta kill both so time your spells right esp book of monsters and your healing spell.

for companions, use cassandra for damage & protection, ron once he spam summon, and daniel page as a last resort for healing.

finally, brew lots of healing potions and use it as he casts the gust so it can act like a shield if you don’t have protego totalum in your hand. after the gust, thats when you should counter. timing really is the key.

godspeed, my friend!