Necromancer Pig

Necromancer Pigs (known in social media as Necro Pigs) are special bonus pigs in Angry Birds Stella.

Strategy
He will start to sing in the levels, causing pigs to turn all the normal pigs into selected pigs and when the pigs are defeated, they will rise from the ground, as the Zombie Pigs, which give a new wave of pigs to the player defeat, defeating Necromancer Pig is a bit hard.

Trivia

 * The Necromancer Pig also appears in Angry Birds Epic but with a different appearance.