This is a "One Command structure" (also called "Only one Command" or "Only one Commandblock").

What is a One Command structure?
A one Command structure adds something "new" into the game, but you do NOT have to download anything!
Every One Command structures are Minecraft Vanilla!

How do I get a one Command structure?
1. Give yourself a commandblock by typing in following command into the chat: /give @p minecraft:command_block
2. Go on the page which is linked here: More Tnt
3. Copy the Command (Make sure you copy the whole command!)
4. Place the Commandblock where ever you want and paste the command in it by pressing Ctrl+V / Strg+V / Command+V at the
    same Time
5. Click on "Done" and place a redstoneblock next to the commandblock!
6. Wait a few seconds!

Won't work? Click here: Help
Credits to: IJAMinecraft  (He made the Video!)

How does this one Command Structure work?

First of all you have to create "Explosive Emeralds" by throwing 10 Gunpowder and 1 Emerald on each other!
After that you have to throw one Explosive Emerald on a Villager. He will turn into a TnT-Shop! (He is invincible after that!)
Now you just have to buy the TnT from him!
(Sometimes the Villager gets new normal Trades if you trade with him! Sry I don't know how to stop that!)
The form of the destruction is always random!

The Different Tnt's

Hot-Tnt:
Makes a bigger Explosion than normal Tnt and it places Fire and Lava around the Explosion

Meteor-Rain:
After a ~10 Seconds delay Meteors (Okay Fireballs) will fly down and cause a huge explosion with fire!
(Warning: It lags really hard! And not only the Explosion, even if you just place the tnt it lags! Requires good Computer)
Don't place this Tnt above the height of 230!

Helpful-Tnt:
This Tnt gives every player in a radius of 20 Blocks Speed V, Strength II, Jump Boost V, Regeneration V and Resistance II for 5 Minutes! It also gives every entity thats not a player in a radius of 10 Blocks the Wither effect for 10 seconds!
This Tnt explodes after 15 Minutes!
The Explosion is bigger than a normal Tnt!

Experiencebomb:
It throws XP-Bottles in 5 Direction! (~ +32 Levels from Level 0)

Timebomb:
Explodes after 60 Seconds! You see how long it takes until it explodes! (It only shows every 10 Seconds (60,50,40 etc.))
You can add 10 Seconds by placing the "10Sec" Item next to the Tnt!
(It doesn't show this too so if the tnt is at the number of 40 and you add 10 seconds it still is at 40! :/ That would take too many commandblocks!)
The Timebomb makes a soundeffect in the last 3 Seconds!
The Explosion is bigger than a normal Tnt!

Remove Villager:
If you place this Item next to the TnT-Shop, he will die and you will get a "Broken Explosive Emerald"!
Throw two of these on the Ground and they will become a normal Explosive Emerald!

Link:
More Tnt