Smite did 55% of my health in one use

I just finished a game of ranked was a losing game I was had really tanked up towards the end but after one fight i saw something crazy on the death recap had done 257 with her flamebreath no big deal and 132 with her R but 2255 true damage with her 55% of my health almost instantly gone. i understand that it has the Dot and her press the attack but still 2255 true damage on smite there are Ults that dont even do that much damage let alone true damage