Its a modpack, where you explore your and other dimensions, fight with bosses, build your base/ city and have lots of fun. There are several new mobs, friendly and hostile ones. New bioms and with that new blocks to build your base/city and lots of new foods you can cook. Of course we cant forget our Ore excavation and Backpack mod. There is also Artifacts which gives you buffs. I added a few mod that add the new blocks, Items and mob from new version as well, such as the Trial Chambers or Happy Ghast.
I would recommend to change the Allocated Memory setting
Setting -> Minecraft -> Allocated Memory to 7k-8k MB
I would recommend 8k