Conjure Fiend (Hell Hound)

You summon a fiendish Hell Hound that appears in an unoccupied space that you can see within range.  

The summoned creature is friendly to you and non aggressive towards your companions unless ordered to attack or is attacked by them. Roll initiative for the summoned creature as it has its own turns. They obey any verbal commands that you issue to them (no action required by you). If you don't issue any commands to them, they defend themselves from hostile creatures, but otherwise take no actions.  The creature can only be dismissed by the original summoning caster or by a banishment spell.  

While summoned the creature(s) gains these benefits:

• Summoned creature can track a targeted creature if presented a piece of the target (i.e. Clothing, Tracks, Blood and Flesh) so long as the targeted creature is in the same plain of existence.
• Can move through burning terrain at full speed with no impeded movement nor receive damage from starting or ending turn in said terrain.
• Gains 20 ft of Magical Darkvision when in areas affected by Darkness Spell
• Gains a +2 to hit in areas affected by Darkness Spell

At Higher Levels. When you cast this spell using certain higher-level spell slots, you can summon an additional creature:  Two with a 5th-level slot, Three with a 7th-level slot, and four a 9th-level slot.