The best torsos for these type of mechs are God Mode and Ultraspade. Metrolens is ok, but it's weak compared to other torsos. You need to have at least 130 energy and 130 heat stats. You at least need 50 regeneration and 80 cooling. You also need 650+ health, and a 10-11 resistance module. These are the basic stats for a heat mech using Meltdown. For Lava Spray use the basic heat build with low regeneration and high cool but with Heat Orb Cannon to pull. Hope this helped you.