I can cast spells during the crow form. So enemy team couldn’t hit me
Here is info about this bug: https://www.reddit.com/r/heroesofthestorm/comments/1ki2l6a/medivh_arcane_rift_exploit/
To reproduce it, you need the ultimate upgrade for Polymorph, which lets you cast Polymorph in an area. Right after you change form, you should use the upgraded Polymorph. This will cause your entity to stay in crow form, but the game will still treat you like a regular hero. This means you can use all your abilities without having to leave crow form.