Using a tonfa and a sword that inflicts corruption status to the enemy. This mini boss has slow and predictable attacks. If he launches itself to the air, it will most probably charge into you. Just run sideways and attack.
Karasu Tengu, giant Tengu with wings like a crow's, has been known to humans since ancient times. They have keen eyesight and hard beaks and fly about as they please, controlling the wind. They have no trouble finding purchase even on sheer cliff faces and use their control over the winds to attack when provoked, making them a troublesome foe.
Tengu are said to be strange echoes of Garuda, Buddhist guardian deity and slayer of serpents and dragons. Reportedly, in some areas, they coexist with humans. The Karasu Tengu are credited with teaching the young Minamoto no Yoshitsune swordsmanship.
Source: https://nioh2.wiki.fextralife.com/Karasu+Tengu
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