On my turn 4 of an Explorer match, I had a tapped Unstoppable Slasher (no counters) and a Valley Flame caller.

My opponent had Voracious Vermin, its rat token, and Bloodletter of Aclazotz (just played last turn).

I played my Steampathcharger, paying for Offspring, and then passed the turn.

Before combat, the card in question was the only one played.
I remember it was modal with at least 2 modes chosen and black.

As the first mode was to force me to sacrifice two creatures and nothing I could do about the second mode, I opted to get the sacrifice over with and read the card after pinging my opponent with the Steampath chargers.

The result was my life total dropped from 20 to -1, and because I was then dead I could no longer check my opponent's graveyard to see what the card was. The obvious assumption is that the second mode ticked my life total down, and Bloodletter doubled it.

But, I've tried an exhaustive search of the available cards and came up empty for a card that A) does both things and B) causes that much damage or life loss. My first thought was Rush of Dread but to do both things requires 6 mana which my opponent didn't have.

Thoughts?