Always a dream in the card game (and usually nerfed the moment it becomes possible), I think there is at least a theoretical possibility based on one of the decks I do run. I think with a huge swathe of luck and cascade it is possible - doesn't even need many mythics to do so!
You need to be playing Kalemne Iroas. First cast Hazoret's Undying Fury (Spell red 21 rare) -The only other spell in your deck is Deploy the Gatewatch (Spell red 23 mythic) This will fetch creatures you need Trample and Quartzwood Crasher (creature red/green 17 rare). I use Ziatora's Envoy and Boborygmos but I think any other 2 trample creatures will do.
The cascade that cast Fury means you have an extra turn - you need Iroas's first ability to give haste.
Then cascade some more to cast Fiery Emancipation (support red 22 mythic)
Your first create attacks from Iroas' haste. It generates a token Dinosaur Beast token and you want to replace your first creature with it. You now have a new first creature, which also gains haste, and attacks. Both attacks do ~30 damage (depending on how Deploy resolved) and Fiery x3 extra for the kill.
I've not yet had that draw/cascade to test! Is 43 mana on turn 1 even possible? Will it give enough loyalty for Iroas' ability?
Thoughts? Can it be improved with mana cheaper alternatives? (is any defense possible?) Are there other turn 1 possibilities?
I'm not sure why the beast token gets haste, but your thinking is pretty good.