At least 2 hours before your party, place all juice cartons, soda bottles, and sparkling cider in the refrigerator. Checkpoint: You are ready to move on when every bottle and carton feels cold to the touch.
(Optional but recommended) The night before, pour pineapple juice or cranberry juice into a Bundt pan or Halloween-shaped mold. Freeze for at least 8 hours or overnight at 0°F until completely solid. To unmold, briefly run warm water over the outside of the pan. Checkpoint: Juice is fully frozen solid and releases cleanly from the mold.
Set out a large punch bowl. Pour in 2 cups chilled pineapple juice, 1.5 cups sweetened cranberry juice, and 0.5 cup pomegranate juice. Stir gently for 1–2 minutes until fully combined. The liquid should turn a deep, uniform pink-red color.
(For green witch's brew version only) Add 3–5 drops of green gel food coloring — not liquid food dye — directly into the juice mixture. Stir gently for about 30 seconds until the color is vivid and evenly distributed throughout. Skip this step if you want the red-purple version.
Right before your guests arrive, slowly pour 2 liters of chilled lemon-lime soda and 750 ml of sparkling apple cider down the inner side of the punch bowl (not straight down into the center). This prevents overflow and preserves carbonation. Stir just once, very gently. The punch should bubble and fizz actively. Do not stir repeatedly or the fizz will disappear.
Using an ice cream scoop, place large mounds of lime or orange sherbet directly on top of the punch, covering the surface. Do not stir after adding the sherbet. It should float, creating a thick, frothy, creamy layer on top. This step takes about 2 minutes.
Place the frozen juice mold in the center of the punch bowl, or scatter frozen fruit such as blackberries or grapes around the bowl to keep the punch cold without diluting it. Drape gummy worms over the rim of the bowl and float lychee-blueberry eyeballs on the surface for a spooky effect.
Serve immediately by ladling punch into individual cups that already contain ice. Make sure each cup gets a bit of the frothy sherbet on top. Throughout the party, add fresh scoops of sherbet and slowly pour in extra chilled soda as needed to keep the punch bubbly.