Hypnosis

One of the more feared gifts in a spellster's arsenal is that of having their will stripped away. But for all its power, hypnosis is also the most fickle of magics. Those who attempt hypnosis of another, must maintain near-constant eye contact and have the ability to bend their will. Even then, the hold lingers only a short while afterwards. The potency itself is widely believed to rely on natural talent rather than any degree of skill or magical strength.

Applied Restriction

There are many methods to avoid being caught in someone's hold, including not directly meeting another's eye. Glasses, especially those worn by near-sighted individuals, are commonly held up as able to deflect any advances.
Then there are those who aren't Nulled Ones who nevertheless claim to be completely immune to the magic where the hold catches them for a moment before it slips. The reason behind this phenomenon is as yet unexplained.