The Rift of Worlds is the place you get two things : The Homonculus, and Grindstones.
Rift of WorldsThe Rift Raid is a three person round where, after forming a party either by inviting your friends or by going through a matching waiting room, you fight a three headed dragon. Rewards include Grindstones, mana, and maybe other things. Grindstones are an interesting thing. You can add them to the runes your monsters have for additional stats. So if your rune has 5% HP and you add a 1-3% grindstone to it, you’ll have (say) 7% HP afterwards. If you power up your rune further and increase it, the grindstone stays (I think).
The more interesting area is the Rift Beast “Raids”. They’re fights. You pick a good team composition and go after them. Light, Dark, Water, Fire, and Wind. Each beast requires a different team and give different rewards.
To get the Homonculus (Meant to be the best monster in game, I am hearing it’s not all that) you need to collect the element crystals – like Water Crystal, etc – and a bunch of magic crystals as well. Once you have the homonculus, you also grind to give it a full set of skills, but this monster has a customizable skill tree.
You can get two Homonculi – One Light/Dark, and one Water/Fire/Wind. I understand the one I’ll want is Water.
Reddit does not describe this place well, but I have an idea where to head with all of this. But first, I am running the Giants dungeon looking for “better” runes – which means either getting the correct Legendary runes to drop, or so many that I have a ton of mana stones to power up Heroic runes and hope they end up good – with the main goal being to improve the stats for Sigmarus. You see, my entire Dragons team is too slow, so I’m starting with him in an attempt to improve their stats to the point where I can run the Dragon dungeon with a high degree of success.