agus is holding the leaf of a mandrake in their mouth for an entire month, using the leaf for the creation of a potion, reciting an incantation (Amato Animo Animato Animagus) on a daily basis, and drinking the Animagus potion during a lightning storm. Once the initial training is over, an Animagus can change at will, with or without a wand.
简单翻译：训练阿尼马格斯的过程其中有一部分是要咬着曼德拉草的叶子整整一个月，然后用这叶子熬制一发魔药，然后每天都要背个咒语amato吧啦吧啦（不翻了），然后在一个暴风雨天喝了这魔药（太玄学了……）。一旦这个初步训练完成，一个阿尼马格斯就可以凭意愿变身，有没有魔杖都可以。（不需要魔杖，这更说明阿尼马格斯倾向于某种状态，而不是一个简单的魔咒。）
还有疑惑的小天使，指路http://harrypotter.wikia.com/wiki/Animagus
里面有一段关于阿尼马格斯并不是单纯的变形术也不是单纯的魔咒的定义，比较绕，如下，我就不翻译了……逃……
According to W.O.M.B.A.T., an Animagus transformation is two of the following: a kind of Self-Transfiguration, a kind of Self-Charm, or a kind of magic that is neither Transfiguration nor Charm. You are asked to pick the statement that is incorrect. This would mean Animagus transformation is either a kind of Self-Tranfiguration but not actually a Transfiguration or Charm, a kind of Self-Charm but not actually a Transfiguration or Charm, or a kind of Self-Transfiguration and Charm.
Applying college-level logic on this, it would be possible for the Animagus transformation to be both a Self-Charm and a Self-Transfiguration because if either the Self-Transfiguration or the Self-Charm statements were wrong, you would have been left with two conflicting statements, one that affirms the status of this and one that specifically denies the affirmation.