Elden Ring players who've been active in the game's PvP experience have likely seen one or two invaders or hosts sprinting at them while set ablaze right now. If you see that and immediately think about leaving the game, you're not alone. Elden Ring has one or two builds players are using now which are considered by many to be "broken" exploits, and they all revolved around one fiery incantation: Fire's Deadly Sin.
The Fire's Deadly Sin incantation isn't one that's just lying around in a chest or an expected spot, so it's not exactly easy to find, or at least it wasn't until word started spreading online. Its effect causes an eruption of fire around the player while the player themselves is set ablaze to continuously deal damage to those nearby. It causes small ticks of damage over time to the user while the effect is active, but it's a negligible amount that won't make a difference in a PvE or PvP fight unless you're also afflicted with poison or Scarlet Rot.
That effect isn't too impressive on its own, but it becomes much more oppressive when combined with another weapon: The Eclipse Shotel. This weapon's unique skill, Death Flare, affixes the Deathblight status effect to the weapon, the same one that causes instant death when the status bar fully fills. The video below from ThatOneGuyManny is just one of many examples online now showing how quickly an enemy dies to this combo.
This combo works because players don't actually have to swing the Eclipse Shotel at all. For some reason, the Fire's Deadly Sin damage ticks seem to apply the statues effects of whatever right-hand weapon you have equipped. So while each hit with the buffed Eclipse Shotel would take a while to apply the Deathblight, you can simply run up to someone instead and stay next to them to apply it in seconds.
Turns out 'Fire's Deadly Sin' combined with the 'Eclipse Shotel' is absolutely broken. Not sure how we were supposed to counter this aside from running away. Might need some tweaking @ELDENRING #ELDENRING pic.twitter.com/WZf0UZjX6P— Shmolty (@TheRealShmolty) March 10, 2022
For right now, the only solution to the problem appears to be running away as the Elden Ring player above suggested. There's also another incantation called Law of Regression which removes stat buffs and the like from a battle and can be used to counter this. That requires the anticipation of an invasion on your part, however, whereas the person invading with the Fire's Deadly Sin combo who invades already has their strategy in mind.
There's also another Fire's Deadly Sin combo involving the Erdtree Greatshield which is garnering similar reactions online, though the Eclipse Shotel one is a bit more egregious. The shield recognizes the ticks of fire damage as incoming projectiles which allows people to "reflect" the damage back at others at the cost of only a few points of health and four FP per shot.
FromSoftware has not yet commented on these strategies, but they likely aren't intended interactions, so it seems likely they'll be patched out in a future update.