Constantine was trying to discreetly keep an eye on everything. At this point, they probably already drained Skender completely and would keep doing so before he could heal and refill with blood. That way he would be in an endless state of healing.
But Constantine still had hope since the demon healed fast. He just needed to stop one draining session and then hurry to disrupt the ceremony. The question was how. Nathaniel had eyes everywhere and witches were tricky to fight. They had so many tricks up their sleeves and these ones were loaded with original and defender blood.
Magic was also tricky and he wasn't sure what it would mean to disrupt the ceremony. He had seen crazy things happen when spells went wrong, but he had to do something.
