With cards like Clockwork Automaton and Blackwald Pixie, it's possible to set up 20 or even 40 damage turns with Metamorphosis!  If you get the discounts on the Automatons with Galvanizer and other combo pieces with Emperor Thaurissan, just play Metamorphosis the turn before you're ready to go, and drop the 20 or 40 damage the following turn!

There's a gameplay video at https://youtu.be/Q3ZiweiXr3I if you'd like to see how it can work.

Enjoy!