1. Have more life than your opponent.
2. Activate Wall of Blood or something similar 'a couple of times'.
3. Play this card.

Are you sure about this design?

I definitely wasn't sure about the design, now I'm still not absolutely sure how it works, either this is a pretty mediocre burn spell or its a kill condition in modern ad nauseum, which could be a small issue. Cheaper, doesn't require red mana, and has less counterplay than lightning storm (spellskite and kira come to mind).

Took me some time to figure out that this spell doesn't do 15 damage on round one... Because five minus twenty equals negative fifteen. That said, this sure is likely to cause a few head scratches.

So at its best this causes a lifeloss 4? Even with stuff that would enable you to have negative life total I don't think the rules would allow this do more than 5. Bump in the Night does lifeloss of 3 by default so this definitely should be more. Maybe... 7? Idk.

They changed the rules recently so I'm pretty unsure on how it works exactly.
I don't think aiming to be conditionally better than Bump in the Night is where I'd want to aim to be, not that I'd know where I'd want to cost this for it to be fun for limited, interesting in constructed. Maybe a card like this is too hard to tune the numbers on and the idea should just be scrapped.