My current issue with Polymorph as cool as it is.
Is that it SEEMS to step on a lot of skills toes and does nothing unique itself mechanically.
It even has a teleport which would be the 4th skillset that has a self-teleport.
But we haven't had our hands on it yet. So everything I say is just fear.
---
If I had to guess what Polymorph is trying to go for tactically...
It is a skillset that is based around keeping to a target. Pull them towards you, bring yourself over there.
With a strong focus on self-buffs and set ups.