You can use Soulfire rune to causes the target to catch on fire. This rune causes 10 damage every 9 seconds for a period of time. How long the effect will last depends upon your level and magic level.
On PvP Worlds and Optional PvP worlds:
- You can use Soulfire rune to catch on fire Boss (for example: Alptramun). This rune is most effective when used as the first attack against a strong creature, causing them to burn while being attacked.
- In Forgotten Knowledge Quest (Fire Portal Boss) You have to attack the Soulcatchers with damage over time like Inflict Wound, Curse, Electrify, Envenom,Holy Flash, Ignite or Soulfire (the runes are recommended because you'll have to wait the spells' Cooldown otherwise) until 3 Corrupted Souls spawned.
Only on PvP Worlds:
It's used mostly in PVP combat to keep the enemy from logging out or fleeing to a Protection Zone. Note that the caster is not able to logout while target burns, too.