I haven't really been able to find a good guide for this. I've found that if you find an enemy at about 60% health, you incendiary missile first. Then toss a thermal detonator, and immediately cast power shot, and as soon as this ends follow up with a rail shot (detonation time on the thermal detonator is about exactly the cast of a power shot) thus their hp goes in a swift succession. This generally does jack up your heat to about halfway-3/4, but theres a 30% chance to make your rail shot free, and your superheated rail decreases decreases your heat by 8. With the burnout ability, you can fire rapid shots to activate your cylinder ability and/or fusion missle, at 30% hp periodic elemental effects increase by 30%. This should finish them off if they aren't crushed already. Does this sound about right?