Let’s get started with the bombs.

make witherstorm like this

First up super TNT

This TNT has an explosion twice as big as a normal TNT. You use this to craft the Formida bomb.

Next is the Formida bomb.

the formida bomb doesn’t actually explode. You can kill witherstorm stage 8 with it and then make it go to it’s next stage.

Now for the stages of the wither storm.

stage 1:

It is a wither holding a command block.

health:700

stage 2:

It is a stage One but with a few changes. 

health: 800

stage 3:

It is stage 2 but with big wither storm head and a tentical.

health:800

stage 4:

Stage 4 has a bigger back.

health: 850

stage 5:

STAGE 5 is the one from the logo of Minecraft story mode.
health: 1000

stage 6:

this stage is stage 6 and it is very cool

health: 1024

stage 7:

Stage 7 it takes 200 seconds till it goes to its next stage once it does you can blow up your formida bomb

health:1024

dead storm:

It is dead.

live again stages:

3 different witherstorms. 

when the storm dies it will drop falling blocks

these mobs are only to make the final battle more difficult 

the final battle will apear after 100 seconds of using the formida bomb on the storm

since the falling blocks are entities when you kill them they drop withered block