DragonField
What if you use legilimency to create a mental gameworld that anybody with a key can join via dream signals: modeled after Dark Souls, but with level ups and attribute points increasing the level of your magic reserves and the (speed, strength, dexterity) buff of your magic. There is also a great plethora of hidden or rewarded spells alongside the in-game items like armor and pets or consumables. There is also a higher likelihood of magic suitable for you based on your mahic-signature and memories to be what you get. Though some bosses have fixed high-level spells if you defeat them. Nightmare memories could be extracted by the gameworld to increase the possibilities\map.