My suggestion:
-2 Ruby Dragons
-2 Quints
+6 Fire Towers
+1 Permafrost Shield
+1 Explosion
To power a dragon and feed all those hungry Steam Machines you need more than a mark. Even without the dragons, the problem remains, so there need to be more towers in there. One lone Explosion won't do much, so add another one, and the same counts for the shield.