how make a procedure that "stop time"

Make a procedure to run the command: /effect give @a slowness 10 255 true.

Then, under that, make a procedure to run this command: /effect clear.

Make the command lines under your username so the game will know the player did the command. If you need more help, contact me.

ZA WURDO

This is a very basic version of timestop. When you think of time stopping you don't think of every living entity being slow. If an entity were to be falling when time "stops" with your version, it would continue falling with just the slowness effect. Also, this doesn't affect items like arrows.

You can change the movement vectors of all entities except you to 0 every tick, which would make entities even stop falling. Additionally, if you want, you could save their movement vectors previous to the "event" as a local variable at every entity, and then afterwards set their movement to that variable, to make them resume their previous movement. 

and how would you do that?

Here's what I've come up with;

https://imgur.com/a/vfKgwKo

You'd create two procedures with the same event trigger, with 4 global variables - as the same two local variables won't work across two seperate procedures.

Note - I forgot to add the part that checks for the item but you'll add that before the checks to see if frozen is true or false

I haven't been able to test it so if you do let me know how it goes!

Actually you could put it into one procedure and use local variables like cerebalpalsyguy mentioned, but check if frozen is true of false beforehand

You guys could make every entity's velocity to be set to zero in x, y, and z except the player. That would work, right?

I tried this, made an item, but since the global trigger is the player right clicking, the event/target entity is the player. It freezes the game trying to right click the item. I can´t find a way to only target mobs. Source entity cant be used because the item dependencies dont allow it. Is there any way to just target the mobs?

Here is my procedure:

https://imgur.com/6sqRJN5

i think u need to make a potion effect that does it on getting the effect

i made it work you need to put it in an effect wich u apply to the person who isn't stopped

here are all the procedures: https://imgur.com/a/l0U8mqT