I don't want to seem like reporting constant bugs, but... this was in the daily challenge, it might be possible during a normal game, but as far as I know, all the ways to reach 0HP have death messages. This was the Jun 21 2022 challenge. 
Edit: Heal has a problem of its own, If you have heal for matched color A and wildcard Colors A and B, you take damage from heal if less than 3 is of color A. It's not just the challenge.
Oh I don't mind it at all! I like it that I'm getting bugs reported in. So today's daily had that "healing deals damage instead" modifier and I think that might be the culprit. 🤔
Oh and by the way, I was investigating that flurry+blink issue you mentioned and it actually seems like blink had an undocumented behaviour of only teleporting to blue tiles (not even affected by chaos). But you still should get a different death message of "Teleported to the void..." when nothing to teleport to.