So we collect heat sparks, level everything up to 10, and then... that's it. They serve no more use, other than to entice others who haven't hit level 10 on everything to health-revive us when we derp up and die.
There's been other suggestions on what to do with the heat: converting it to crowns (no) or energy (double-no), using it for a super-charged skill during the level like a large knockback or speed increase or whatever (meh).
Here's my idea: have the heat go on to the weapons beyond level 10.
Basically, the heat scale would go as usual from 1 to 10, then if everything in your inventory is at 10, it would extend into an "overheat" section where the damage output or protection level would scale continuously up to an "11" level as you collect more heat.
This overheat would then cool off again over the next, say, 24 or 48 hours back to just a regular level 10.
I thought this was going to be about being able to turn heat into UV rolls. I was disappointed.
I don't really like the idea of this just because you would feel like you need to heat your stuff prior to doing new content. Also, it makes it harder for 000 to balance, since they don't know if your items are level 10 or 11.