Successfully Cleared Nightmare Floors 5 and 6! But Had a Tough Time Against the Seal Knight

Successfully cleared Nightmare floors 5 and 6! However, I had a really tough time against the Seal Knight 💦 By the way, I'm still using the Dancer's 'Returner' this time. Normally, I take advantage of the amulet's effect, enchanting defense cards with 'Dance' (damage when changing card order) or 'Impact' (damage when it becomes the first card in hand) to swap cards, increasing defense while attacking. It seems that if you don't repair the keys, the final boss branches into two patterns: the Golden Beast or the Seal Knight Patram. However, the 'Ultimate Purification' card used by the Seal Knight Patram and its second phase effect 'All Enchantments/Runes Reset for Both Sides' are truly my nemesis. My accumulated 'Dance' and 'Impact' get reset, forcing me to build them up again from scratch. On top of that, the enemy's attack power increases with each hit, making prolonged battles dangerous. If I discard defense cards, my enhanced defense values disappear and revert to their base values, making it impossible to defend. I was even reduced to 2 HP on floor 5 💦 As a countermeasure, I realize I need to either use blessings like 'Soul Steal' or one-time use cards like 'Mask of the Heart' to remove 'Ultimate Purification,' or secure a way to immediately restore defense right after evacuating cards to the discard pile just before entering phase 2, or perhaps use evasion-type cards. 🤔