And hellhounds don't shoot fireballs. They have the elemental attack ability. Which is limited to (Magic rating) Meters. Aka 6 meters.
Do you have a reference for that? I've never been able to find anything in 5e that limits line-of-sight spells or powers to anything other than how far the mage/critter can see.
page 396
"The power is a ranged attack, with range increments of (Magic) meters, using the critter's Exotic Ranged Weapon skill + Agility [Physical} to attack."
