When the dark wave of mana hit Midnight and Remey, the two had taken their best defensive positions, but the force had still landed cleanly. The force had been enough to send the two tumbling and leave clear bruises all over Remey's arms. If Mndight had not deflected some of the attack, then Remey would easily have a broken arm.
Midnight wasn't looking well either. The attacks had cracked the skeletal armor skill and some of her scales. Her higher resistance and tough scales had taken the attack and lowered the damage. However, she felt every bit of what had affected her. The slight decaying aura that had come with the attack was more potent.
This affects was because of the death mana mixed in to the attack. It was what left damage that was not being healed as Walker reached out with the heal skill. Therefore, Walker realized that the only way he could erase it was with direct healing using life mana or by using more natural mana to boost his healing.