How to increase projectile damage of the spells such as fire spells, I even try to add damge: 1000 but it wont work, but it will work for arrowrain

The fire spell doesn't do direct damage, it just causes fire. There's no way (at least not in Magic) to make fire do different damage.

If you wanted to make a custom spell for that, you would combine the Fire action and the Damage action, so it does both.

there is no way to config those damage and fire action together using magic plugin ? if there is a way how can I config it and the documentary to create custom was removed, can you send me latest one or teach me to config it ? :)

Documentation was not removed, but really you just have to learn by example. Check the wiki:

https://github.com/elBukkit/MagicPlugin/wiki/Customization

There's just too much there to have it all documented- the default spells are the documentation.

In this case, you would look at the fire spell and modify it. Here's probably what you want- this would go in plugins/Magic/spells.yml :

fire:
    parameters:
        damage: 10
    actions:
        cast:
        - class: CustomProjectile
          actions:
          - class: AreaOfEffect
            actions:
            - class: Damage
          - class: Disc
            actions:
            - class: Cover
              actions:
              - class: Burn

I took the list of actions from the fire spell:

https://github.com/elBukkit/MagicPlugin/blob/master/Magic/src/main/resources/defaults/spells/fire.yml

And I added an AreaOfEffect + Damage action set. This will damage any entities within a radius of where the spell hits. That radius will match the radius used in the "Disc + Cover + Burn" action set to cover a disc of blocks with fire.

I then added a "damage" parameter to control the damage done by the Damage action.

okay Thanks :)