Akihiko_Matsui said:
Thief
In addition to the effects that can be stolen by Aura Steal, Larceny will allow you to steal monsters' special abilities as well. In the case where a monster has several enhancements active, the special ability will take the highest priority for stealing. When the effect is stolen, it will be removed from the monster, and the effect will be granted to the player that stole it. Even if you steal the ability from them after it has been used for a bit, the effect duration will be reset when stolen, so you will gain an effect duration that is the same as if you used it yourself.
However, there are some exceptions. Astral Flow cannot be stolen. This is due to the fact that the specs for Astral Flow used by monsters is different than that of what players use, and it is a type of ability where the effect is elicited upon use.
One more ability that is treated specially is Meikyo Shisui. While you will be able to steal and use Meikyo Shisui from monsters, it will not be possible to stop them from using their weapon skills. This is due to the fact that the behavior of monsters with this ability is different.
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Camate said:
"Steals one beneficial effect from the target enemy.
* New special abilities cannot be stolen."
should answer all your questions.