How can I use fireball on blocky? I've tried, but it's not working.
Hm weird. Could you post a screencap or a public link to your code? Are you using an event block?
It looks like you just named a drone fireball instead of actually creating a fireball.
You could try making a fireball wand and summon fire that way: http://mod.learntomod.com/badge_builders/3188?sequence=9084&position=8
There's also a fireball or explosion particle you could try located under the particles section in the Blockly menu.
This badge will show you where to find the particle blocks: http://mod.learntomod.com/badge_builders/2812?sequence=9049&position=5
Definitely try testing the mod in minecraft - it may be too advanced for the simulator to render properly.