Looking for an opportunity to flex his power and take a worthy head back with him as a trophy was the reason why Rehabab had been quite calm about his enemies moving to summon a divine being.
Rehabab was a champion for his lord, he was not a common soldier or commander looking to eke out a swift and easy victory. No, what Rehabab sought was a battle of tension, fear, courage, grit, death and most important of all one that would push him to his limit.
While playing around with Hannah, Rehabab had been waiting for his opponent to be summoned when he had felt the evil mana and quickly made a few deductions on what might be happening.
Initially, Rehabab had planned to relax and let the situation play out, but then he had seen Blake, Hannah's expression saying that she knew the man and in that instant, Rehabab had felt that perhaps he had been a bit too lax about the situation.