It is sold by Merchant.
Unreal is the strongest prefix for Flare — +15% damage, +10% speed, +10% crit, +15% knockback (ranged only).
Flare deals 1 base damage. Use the DPS calculator to see expected damage per second with prefixes and crit applied.
Flare is used as an ingredient in 3 recipes. See the "Used to craft" section above for the full list.