Suggestion: elemental dragons
Currently, the next elemental dragon is indicated by an image on the mini map.
I suggest indicating the next element by changing the environment of the dragon pit. For example, a few minutes before the fire dragon spawns, the water in the pit dries up and tongues of fire ignite nearby trees/rocks etc. This isn't a necessary change, and is definitely a hefty graphics job (you would probably need ~15 seconds of animation to make a smooth transition) so I don't think it should be planned for the near future. But... it would make team communication and vision control over dragon a higher priority, which I personally believe is a strategic component of gameplay that should be enforced and encouraged.