I've always wanted to make an attack using Hopperbin like a Kamehameha but I never understood how it worked :( Someone once told me it had something to do with "instances" but I don't know how to do it. Someone please help :)
Lol, Ive always wanted to make attacks like that too. So I searched around a bit and came across a playlist of scripting tutorials by Friaza. He demonstrates how to make OnKeyDown attacks such as fire balls and shields. Also Chapter 1 in the ROBLOX Wiki scripting book teaches you a lot about Instances and how to manipulate them. I wish you good luck.
http://wiki.roblox.com/index.php?title=Scripting_Book#Chapter_1
https://www.youtube.com/channel/UCRH_AFdWqNEJuqlKjH0IU1Q
These might help you.