No need to change the Punch 2 Bow. It is what it is.
TNT BOW and Knockback 5 Slimeball exist to add fun and challenge people.
Throwable Creeper is useful if you aim well.
Combining two items would take a lot of time.
Don't know about the launcher thingy.
What is the suggestion about?
Anti-Tpa Trapping/ Killing
So this suggestion is all about tpa killing. We all know that /tpa is where we have trust issues with some people. So here is my suggestion to this problem:
1.) Give Invulnerability...