on rightclick:
if player's tool is nether star named "&4Reroll Item":
set {_MHP} to random integer between 8 and 20
set player's max health to {_MHP}
remove 1 nether star named "&4Reroll Item" from player's inventory
message "Set Health to %{_MHP}%"
command /rerollget:
permission: op
trigger:
give player 1 of nether star named "&4Reroll Item"