1. Fishing event giving hundreds of goddess graces, merc pots, element stone materials, and magic elixirs.
2. Feed the bunny event for free various runes.
3. Enhance and Enchant bonus and BOGO items.
Magic elixirs from fishing event helped enchant some of my Arisha's armor with r7 scrolls. Managed to +13 my Lann's spears from +10 in one shot. Got my Arisha's weapon to +12. Girlfriend made two +14 scythes. These gave me a reason to play my other characters more often.
Hardly worthless events. Keep them coming Nexon.