When pRO closed in March 2015, Ragnarok Online was at Episode 14 El Dicastes. I was able to migrate my characters in the International Ragnarok Online (iRO) server but I only started playing there in November 2016. I was on hiatus for almost 2 years.
I was updated with RO contents while playing at pRO. My AB was at max level at that time (150) and was able to finished the required quests to obtain the accessory to instantly teleport to El Dicastes.
When I started playing at iRO, I was a bit shocked at how the game progress in 2 years. The major one being the level cap -- it increased from 150 ato 175. That's a lot of grinding.
Episode 15 Phantasmagorica was also launched along with the Crimson Items. These items are for level 70 and up, so it's for my low level characters. Crimson Items is similar to elemental weapons but it has slots for cards i.e. Crimson Mace, which could either be Neutral, Fire, Wind, Water, Earth, Holy or Dark.
Some of the other things that I need to learn right now are the following (which proves that there are still a lot to learn/experience in RO):
1. Enchanting weapons
2. Desocketing and Slotting gears and weapons
3. New Maps -- Verus City, Mora Town
4. Instances -- Nightmare Toy Factory, Old Glast Heim, Jitterbug
5. Biolabs 4 Entrance Quest
6. Overseas Care Package (OCP) Items
7. Vicious Items
8. Episode 16 Banquet for Heroes
9. New Map: Rock Ridge (coming this June 2017)
10. New Cards