Hmm, maybe I'm weird, but that's not how I'd play steam machines.
The damage is good late game, sure, but early game their synergy with rage potion is way more beneficial.
Lava Destroyer
Turn 1: 7 damage
Turn 2: 16 damage
Turn 3: 27 damage
Turn 4: 46 damage (rage potion)
Turn 5: 67 damage
Turn 6: 90 damage
Turn 7: 115 damage. Deadface
Steam Machine (upgraded)
Turn 1: 15 damage (rage potion x 2)
Turn 2: 33 damage
Turn 3: 54 damage
Turn 4: 78 damage
Turn 5: 105 damage. Deadface
Turn 1: 12 damage (rage potion x2)
Turn 2: 28 damage
Turn 3: 47 damage
Turn 4: 69 damage
Turn 5: 94 damage
Turn 6: 122 damage. Deadface
Sorry. It takes six turns, not five.
Furthermore...
Turn 1: 3 Health
Turn 2: 3 Health
Turn 3: 3 Health
Turn 4: 3 Health
Turn 5: 3 Health
Turn 6: 3 Health
Seems easy to control imo
. Especially versus lava destroyer...
Turn 1: 1 Health
Turn 2: 3 Health
Turn 3: 5 Health
Turn 4: 1 Health
Turn 5: 3 Health
Turn 6: 5 Health
Turn 7: 7 Health
Now you could argue that over the first six turns it still averages 3 health, but keep in mind that the difference between 1 and 3 health is negligible; almost everything that kills 1 health will kill 3 health. However, the difference between those two turns with 5 health and 3 health is much larger and will allow you to survive a larger variety of control on those two turns.
Also of note is that you don't NEED to use rage potion on a lava destroyer. You may say that you don't need to use it on the steam machine either, but steam machine minus rage potions verse lava destroyer minus rage potions = lava destroyer is faster. Add that on to the fact that you need to rage potion the machine twice on the first turn to achieve that fast kill, and on that turn you may not know if your opponent has much control. However, 4 turns in, when you would rage potion the destroyer, you will have a much better idea of what kind of control the opponent has and could make a much more educated decision.
Now let's look at costs for each over their turns.
Steam Machine:
Turn 1: 7
6
(2 rage pots)
Turn 2: 7
8
Turn 3: 7
10
Turn 4: 7
12
Turn 5: 7
14
Turn 6: 7
16
Lava Destroyer:
Turn 1: 5
Turn 2: 5
1
Turn 3: 5
2
Turn 4: 8
3
(rage pot)
Turn 5: 8
4
Turn 6: 8
5
Turn 7: 8
6
Now which seems more cost effective to you? The lava destroyer, for sure. Also of note is that you can easily play a lava destroyer on turn 1 with a cremation and then with a mark of earth you have ALL of the costs covered. Good luck getting the steam machine out on turn 1 and rage potioning it twice
. So essentially you won't every play the steam machine until turn 2, so we could add in a turn before it starts doing damage and make it take 7 turns to kill, which means it takes just as long for a lava destroyer to kill as it does steam machine. And lava destroyer costs a little more than half as much with quanta much easier to get. Oh and the lava destroyer is more flexible with respect to using or not using the rage elixir.
Finally, as one last point, it should be noted that playing the steam machine on turn 2 and rage elixiring it twice would be a BEST CASE scenario as opposed to playing a lava destroyer on turn 1 is average with cremations (which would also be the best way to go about getting fire quanta for the steam machine). More often than not, you wouldn't play a steam machine and rage it twice until turn 3, so it would actually take LONGER for a steam machine to kill versus a lava destroyer in the case where a deck with solely lava destroyers, cremations, and rage elixirs is up against a steam machine, cremation, and rage elixir deck.
