Although it seems similar to the Ink Mountain brainwashing technique, it should actually be much weaker, more akin to a one-time spell, forcibly imposing the caster's will and influencing the target's mind. For low-intelligence creatures, it might be okay, but for intelligent beings, it probably won't be very effective.
After all, if the target is a mage of the same level or stronger, this kind of magic naturally won't have much effect. It will most likely be blocked by the mage's various protective spells and tools. Even if it's not a mage, one can resist it with willpower, and the magic will naturally lose its effect once the magic power is exhausted.
However... the Whirlpool Gang, these mentally unstable lunatics themselves, are indeed a group of low-intelligence creatures...
