Alchemist's Fire

This sticky, adhesive fluid ignites when exposed to air. As an action, you can toss this flask up to 20 feet, shattering it on impact. Make a ranged Attack against a creature or object, treating the alchemist's fire as an Improvised Weapon.

Damage: On a hit, the target takes initial damage based upon the potion's Rarity type 2D4 for Common. At the start of its next turn, the creature takes additional fire damage that is 1d4 less than its initial Rarity damage (minimium of  1d4) . 

Extinguishing Flames: A creature can end this damage by using its action to make a DC 10 2D4  DEXterity check (as a base DC for the Rarity type of Common) to extinguish the flames.  The DC  increases by 2 for each increase in Rarity used (DC 12 for Uncommon). Reduce the DC by 2 for each turn the creature fails the DC check (Uncommon DC 12 / Common DC 10 on the creatures next turn if failed on first attempt at DC 12).
 
Instability: As the concentration of highly combustable material heightens, so does the risk. Common Alchemists Fire has an instability of 1%, increasing by a further 10% for each level in rarity. On a missed Attack, roll a d100 against the Instability level of the Alchemists Fire. If the result is lower than the Instability Rating, the container fails and the fluid ignites the wielder, dealing damage as normal.

Notes: Damage: Fire