Hey guys,

Some of you might know the anime One Piece, some may not. 
So first I am going to explain what Gear Second is.

Gear Second is a special ability in which someone is faster, stronger and hungrier.
The ability is activited by speeding up your own blood circulation.

So I thought it would be nice to recreate this in Minecraft.
WARNING: Advanced redstone knowledge is required!

Tutorial
1. Create a variable with the scoreboard command. When a certain amount of points is reached, a command block asks you if you want to activate Gear Second.
I used "Power" as variable. For each kill you will get 1 Power.
/testfor @p[score_Power_min=100]
A clock must be attached to this command block.
When 100 Power is reached, a redstone signal will come out of the command block leading to this command block:
/tellraw @a {"text":"","extra":[{"text":"Do you want to activate "},{"text":"Gear Second]","color":"gold","clickEvent":{"action":"run_command","value":"/setblock <x> <y> <z> minecraft:redstone_block"},"hoverEvent":{"action":"show_text","value":{"text":"","extra":[{"text":"Gear Second gives you more speed and power!","color":"gray"}]}}},{"text":"?"}]}
Use this command to ask if a player wants to activate Gear Second.

2. The X Y and Z coordinates have yet to be chosen, since ~ ~5 ~ doesn't work for some reason. Place a comparator clock (Place a comparator, click it once, and make a redstone trail coming out of the comparator. Connect this trail to one of the sides of the comparator.) next to the place where the redstone block would spawn. Connect the trail to a timer.

3. Lead the redstone trail that comes out of the comparator to command blocks. This command is for one of them:
/execute @p ~ ~ ~ particle smoke ~ ~ ~ 0.5 0.5 0.5 0.01 100
It will not kill you for some reason. The smoke is typical for Second Gear, it doesn't have any real function.
Put these commands in other command blocks, these are the Second Gear effects:
/effect @p 1 3 2
For speed
/effect @p 17 3 1
For hunger (Gear Second gives you intense hunger)
/effect @p 5 3 2
For strength

4. When the timer (for example 30 seconds) has stopped, the redstone block must disappear via
/setblock <x> <y> <z> minecraft:air
The scoreboard objective must be either reset or reduced.

Summary:
Redstone clock --> testfor certain amount of points --> ask for Second Gear --> Second Gear activated --> redstone block triggers clock --> clock triggers timer --> clock gives you smoke particles and effects --> timer has stopped --> redstone block disappears --> amount of points reduced/reset.

I am trying to make this better so you can have a greater experience.
Updates will be posted soon!

If you have any questions, leave a comment below!

Have fun!

- Welp