How to add a code block:



Anyways you don't have to use commands for abilities, you can use functions unless you want it to be a command.

you don't have to use "if {_waited} > 16 seconds:" literally pointless all you have to do is add a "stop" after the cooldown message so, and then set {astraldrop.%player%.lastused} to now

Code (Text):

1. message "&cYou're on cooldown! Wait 5 minutes before using this again!"
2. stop

Here's the astral drop using a command

Code (Text):

1. command /astraldrop:
2.     trigger:
3.         set {_waited} to difference between {astraldrop.%player%.lastused} and now
4.         if {_waited} is less than 5 minutes:
5.             message "&cYou're on cooldown! Wait 5 minutes before using this again!"
6.             stop
7.  
8.         if player has ghast tear:
9.  
10.             apply potion of regeneration 2 to player for 6 seconds
11.             apply potion of health boost to player for 14 seconds
12.             message "&7You have used the power of the &f&lAstral Drop &7use this short burst of power wisely."
13.  
14.             set {astraldrop.%player%.lastused} to now
15.  
16. on right click:
17.     if player's held item is ghast tear:
18.         make player execute command "/astraldrop"

Here is how I'd do it with functions

Code (Text):

1. function astraldrop(p: player):
2.     set {_waited} to difference between {astraldrop.%{_p}%.lastused} and now
3.     if {_waited} is less than 5 minutes:
4.         message "&cYou're on cooldown! Wait 5 minutes before using this again!" to {_p}
5.         stop
6.     if {_p} has ghast tear:
7.         apply potion of regeneration 2 to {_p} for 6 seconds
8.         apply potion of health boost to {_p} for 14 seconds
9.         message "&7You have used the power of the &f&lAstral Drop &7use this short burst of power wisely." to {_p}
10.  
11.         set {astraldrop.%{_p}%.lastused} to now
12.  
13. on right click:
14.     if player's held item is ghast tear:
15.         astraldrop(player)

Also I saw that the way your using messages is also incorrect, messages require a quotation mark before and after like how I used it, also a faster alternative is:

Code (Text):

1. send "hello world"

EDIT: I went out of my way, and added the tabs so I can test your skript, next time use code blocks, and show errors to get faster help.