Yaaaay :) Didn't even take any damage.
So, the way that Burn works is that it sets the highest value, ex if you have 15 Burn and gain 10, you only lose 10 Thorn if you have it but more burn is not added. If you gain 20 Burn, you gain 5 Burn since it set your Burn to 20. Its hard to convey this in a short text but i have updated the tooltip for it now and i hope it got more clear now ^^