Warning this is during Ofnir awakening event. This is just a team for his (Ofnir) event.
Make sure you have the high aqua rings for this boss.
Also make sure to have equipment and/or units that attack multiple times, even if it equipment that says 'attack 6 times with *18% damage each.'
Also if you are wondering about Sara Blood Spiller skill {Damage against beast up}, it's an awakening skill which required 50 skill Crystal Earth, 1 Love Rune [Earth] (Loewe), 500 Arena tokens and 500 Friend Token to unlock level 1.
This was a close call.
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https://www.youtube.com/watch?v=Q-p_DnvkdOA