This is the official list of banned items on Cosmitopia.
-Snowman Cannon
-Drill Containment Unit
-Clentaminator
-Coin Gun
-Meowmere
-Star Wrath
-Sticky Bomb
-Sticky Dynamite
-Dynamite
-Portal gun
-Nebula Arcanum
-Nebula Blaze
-Explosives
-Holy Water
-Unholy Water
-Blood Water
-Rotten Egg
-Last Prism
-Sniper Rifle
-Solar Tablet
-Naughty Present
-Pumpkin Moon Medallion
-Rainbow Crystal Staff
-Lunar Flare
-Terrarian