Ranger Fireball

[Stuvius]

Ok all, this may be crazy but I just had this idea and I had to put it out here and see what the forum thought. I am a relatively new D@D player and DM (I have been playing for about a year and a half/just finished DMing my first campaign). I am playing a ranger in an upcoming core only campaign and I wanted to find a way to hybridize a fireball from a fireball necklace and an arrow. If the DM would allow, could I tie or in some other way affix it to the arrow before it was fired? Normally a fireball from a necklace hits at 70 feet with no attack roll. Would this hold true or would the arrow have to hit? What do you guys think?

[PaintByBlood]

It seems fair enough to me. I would probably require some (fairly low) craft check to do the affixing in the first place, but after that I would treat it as I would treat a ranged attack targeting a square - keep the ranged increment of the bow, a miss causes it to end up some randomized distance away. I think the rules for this are in the later part of the PHB.
I may also say you should be able to directly target someone and remove their chance to save against the damage. In this case, you may want to look towards the rules for Meteor Swarm.