Psst, you. Yes, you, Crystal Isles player.
It is used in the making of propellent which in turn is needed for both flamethrower fuel and flame arrows. You also need it for crafting the flamethrower. - Bad
The bottom left islands of ragnarok give a good amount. Look out for smaller, golden rocks.
Make a trap next to the wyvern cave. Kill wyverns u will get sulfur and when u killed them all u get free eggs.
It look like cheese
A helpful tip should include more words
There is a massive sulfur spawn on ext in the bottom left. You can get around 3k