Fire-Blood Venom (5e Equipment)
From D&D Wiki
Price per dose: 300 gp
A virulent hybrid of snake venom and alchemist's fire, this poison causes the blood of its victims to ignite.
This poison is very difficult and very dangerous to make, and even the slightest error can result in catastrophe. To craft this poison, you must succeed on a DC 25 poison-crafting check. You make this check at a disadvantage if you are not proficient in both an Alchemist's Kit and a Poisoner's Kit. On a failed check, all ingredients are destroyed and you take 1d6 fire damage. On a check failed by more than 5, all previous effects are applied and you must make a save against this poison. On a critical failure, you suffer all previous effects and automatically fail your save.
To attempt to craft this poison you will need 50 gold worth of snake's venom and a bottle of alchemist's fire.
After the poison is administered, the affected party must make a DC 15 Constitution saving throw. Creatures with fire resistance have an advantage on this save, while creatures with fire vulnerability have a disadvantage. On a success, their body suppresses the flames and they take no effect. On a failure, they take 2d6 initial fire damage as their blood ignites and they are poisoned. Each round the afflicted may attempt the save again, however the DC increases by one each time they fail (To a maximum of 20). Additionally, every time they fail they take an 1d6 fire damage. This damage increases by 1d6 for each time they've failed (To a maximum of 10d6). If they succeed, the damage dice decreases by one and if it reaches zero the effects of the poison end.
Should a creature die while under the effect of this poison, their body will ignite. Their body will be reduced to ashes in 1d4 turns, along with any equipment that they are carrying unless that equipment is specifically stated to be fire resistant.