As a minecraft idea I think it would be a great idea if we could ride Ghasts and use there powers to kill other mobs in the game. I made a quick sketch on paint of what it may look like. Also before they can ride the ghast they would need some blaze rods that could attract them (can be changed to a different item). Then the player to right click with the manual on how to tame it to ride the Ghast, you could be also able to shoot arrows whilst mounted on the Ghast. Also use there attacks, then they could level up making them deliver increasingly more damage. The levels should be capped to 20 and once there levels gets to max the Ghast could obtain golden armour with 120 health. The can regenerate health by giving them pig zombie's flesh, but also lowers there attack damage for some time.
Too much?