What you need:
2 moonflower plants (you can find the seeds at target) 
2 Morning Glory plant (you can get it at dollar tree) 
Fruit Punch (they wont know its a coma potion xD) 
Knife or hands 
Small bottle (about the size of your hand as a fist)

Firstly get your small bottle and fill it with fruit punch. Cut/rip up the moonflowers and morning glories into small pieces then put it in the bottle.Think of the person going into a coma and say Make this potion give a coma To whoever drinks it They will be in a coma for a while Or maybe forever Make this potion give a coma Make this potion give a coma So mote it be Now all you have to do is make people drink it.