Tap the game screen to make the witch fly. Collect stars, but avoid the flying pumpkins, ghosts, the pumpkin scarecrow, and the purple witch.

After you collect a star the witch is encased in shield for 8 seconds during which time she cannot be damaged.

The witch autoshoots so you can aim to destroy the oncoming Halloween ghouls.

Collect the stars to gain an 8 second shield, avoid all other objects.