Unwilling to accept the truth that had been presented to him, Daneel went over all of the Anti-Enthrallment spells that were present behind the third seal.
Enthrallment was something more complex than Mind Control: in the latter, specific instructions needed to be given, but, in the former, a vague sense of admiration would be born that could be used to basically achieve anything. In other terms, it was an advanced version.
Indeed, just like both the Ancient Dragon and the system had said, the spells he found were too flashy, and without a doubt, the Big Four would be able to notice easily.
For example, one of the spells dictated that those under the effect of the Enthrallment could be subjected to a complex formation that would wipe their mind and 'reset' their preferences and likes according to what they were before the spell was cast on them.