The Firesoul Potion is a new potion in Avalon. It increases melee damage by 10% and gives all swords the ability to inflict the On Fire! debuff on NPCs. It has a duration of 4 minutes. To craft one, you must gather: 1 Bottled Water, 1 Deathweed, 1 Fireblossom, and 5 Fire Shard at a Bottle.
This potion is in two other mods, with the name "Fireheart Potion." The other mods are Project En and mbran's mod.