Subzero Heatsinks
Subzero Heatsinks is an artifact for Drake that allows you to have up to 3 negative stacks of Heat.
Clarification
Combustion Engine will use the absolute value of your Heat for determining how it moves.
Flash Point will treat your Heat as zero if used with negative Heat.
Strategy
This artifact allows you to play cards that lower your Heat before cards that cause you to gain Heat. Cards like Hot Compress and Desperate Measures overheat you the turn you play them, so the only turn you normally have to mitigate that with negative Heat is the same turn you play those cards. With this card, you can apply the negative heat on any prior turn, too. It allows Exothermic Release to be much more effective, giving you a heat cushion when playing it - that card otherwise needs to be drawn at the right time, with the right cards, to have its full effect.
You still need to have your Heat economy be overall net-negative if you want to prevent overheating in the long run, even with this artifact. Notably, if you're not using Heat cards, you can use one Exothermic Release to make Combustion Engine a powerful card for the rest of the fight.