Form

Forms are Dervish-only skills that temporarily transform the user into an avatar or representation of one of the Gods. Forms alter a player's physical appearance, as well as provide powerful positive benefits. Forms have very quick recharge times, but if the player succeeds in activating a form, the skill will be disabled for an additional 2 minutes. Forms do however become enabled again if you kill a boss during this 2 minute period. All five forms currently in the game are elite skills.

When a form ends, you are interrupted. This is a hard interrupt that cannot be avoided with Mantra of Resolve or Glyph of Concentration.

While in the form shape, the player's character will have alternate character animations (emotes, attack animations, casting animations, ...).

A character can only have one Form active at a time. Forms can only be prematurely ended by death or entering a new form.

Skills
Form skills cannot be copied using Arcane Mimicry. This is presumably because of their extremely extended duration that can be used to keep the Form up at all times using the spell.