Potion Attack

Set up stares like this

Step 1: Corridor

Make a corridor as long as you want

Step 2: Drop

Make a drop like this so the player does not know what's coming

Step 3: Potions

Fill the dispensers with potions of harming

Step 4: Redstone

Put the Redstone over the dispensers

Step 5: Activated

Switch the world to survival unles you made it in survival so the next player to try to steal your stuff will get recked by magic