Chakram Skycrag

Pyroknight is not in the deck because the overabundance of one cost units is not very feasible for a tournament environment and also not very effective against the multitude of Time and Argenport decks which focus on putting large units on the field. All of your one drops cannot fight anything bigger than an Argenport Instigator, and without support, you're left unable to attack and push their life total with your small units while your opponent just gets further and further ahead. Polymorph is in for the same reason as well. Much like in Burn Queen, small units seldom win the game for you: it's the flyers and evasive units, which are cards like Crimson Firemaw here and Impending Doom in Burn Queen. When those cards are the ones winning for you, you'd rather make sure their Sandstorm Titans and other big flyers are dead so you can just keep swinging, and Polymorph accomplishes that job.

I agree that Rampage isn't incredibly powerful, but it is a card that helps you continue to attack, which is what you always want. In that vein, it's often just Torches 5-6 when attacking while also serving the added bonus of ensuring your grounded Chakram units get damage through when chumped. I encourage you to try the deck before knocking it entirely, as it has been in development for quite some time and performed extremely well against a tough field.