Crows

 are NPC's available during the Dark Magic Mini Event and Flying Solo Mini Event.

They serve as the usual roaming characters that must be collected by tapping. They spawn in groups at various times (after each group has been tapped).

About
Diablo is Maleficent's pet raven and the secondary antagonist in Disney's 1959 animated feature film Sleeping Beauty.

He appears to have a similar role to the raven in Snow White and the Seven Dwarfs. However, he plays a larger role in the storyline and is in almost every scene that Maleficent appears in. In addition, unlike the raven in Snow White, he is completely and genuinely loyal to Maleficent and, unlike the rest of her servants, he is competent and easily succeeds in his task to find Aurora.

Trivia

 * also appeared during the first two Clean Sweep Mini Events due to a glitch in some games.