Conjure Dragon

You call forth a dragon servant. Choose an open 15-foot cube within range. A dragon of challenge rating 5 or lower appropriate to the area you chose appears in an unoccupied space within 15 feet of it. 

The dragon is friendly to you and your companions for the duration. Roll initiative for the dragon, which has its own turns. It obeys any verbal commands that you issue to it (no action required by you). If you don't issue any commands to the dragon, it defends itself from hostile creatures but otherwise takes no actions.

If your concentration is broken, the dragon doesn't disappear. Instead, you lose control of the dragon, it becomes hostile toward you and your companions, and it might attack. An uncontrolled dragon can't be dismissed by you, and it disappears 1 hour after you summoned it.

The GM has the dragon's statistics. 

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the challenge rating increases by 1 for each slot level above 5th.

Sample Dragons