If you have Rylais dragon is crazy amount of utility and sustained damage.
You gotta play with that in mind. It's stronger than having your ult but now you prefer a sustained fight or siege.
Dragon lasts 45 seconds which is enough time to comfortably get to enemy base and still have some time with it (I think it's like 15-20 seconds)
If you teleport Dragon just sits there. So if you're going to teleport command it to the spot your teleporting to.
btw, dragon doesn't have a leash range? What?
Seriously. Sit in a bush and just be dragon for 45 seconds. It doesn't zip him back to Morde if he goes too far away.
A lot of people are saying Morde won't hold up but the same weaknesses he had in the past are still there. The damage was just moved around. Phage, Rylais, and Lucidity boots gives you a fairly decent mid-game. His solo potential is less than before but with coordination Morde is a pretty powerful tool for a team to have.
Once it hits live and people have some time with him. I think you'll actually see one or two damage nerfs and a couple compensation buffs that make him less confusing to understand.