So this is the issue that everyone will inadvertently run into when upgrading to a usb type-c device. While usb Type-c is the future of smartphones it will take some time to get fully adapted to it. I have a total of 3 USB Type C chargers and only 2 actual cables. On the other hand I have countless micro USB 2.0 chargers.
What do you do when you can't find your HTC 10 charger and your Nexus 6P charger is the only charger around. Well the fact that it actually has a Type-C cable the natural decision would be just to use the 6P charger. "Drewmor" did just that. He charged his HTC 10 overnight with the 6P charger. When he woke up the next day he picked up the phone to discover it was hot enough to actually burn his hand.
For now I would suggest that you use your HTC 10 charger only. Of course soon there will be plenty of third party chargers that are Qualcomm 3.0 certified which you should be able to use with the HTC 10. There actually already are a few QC3.0 certified chargers out there.
via XDA