You eat at least a portion of the brain of another creature's corpse. Roll a d20. On a 15+, you gain the creature's memories and knowledge to some degree, recalling any important fact known to the creature - family history, recent events, the general layout of the creature's stomping grounds, details about the creature's death, important plans, passwords, magic item command words, and similar tidbits. Skills, feats, spells, and other such knowledge cannot be obtained in this fashion.
Once you roll to determine whether she recalls a fact, she cannot attempt to recall that fact again.
You temporarily strain a living target creature's muscles in a very specific way. The target feels a sharp pain when they make an attack, suffering disadvantage on attack rolls for the duration.
You call upon the darkest forces in all existence to rain destruction down upon the land in a 200 mile radius originating from you. All creatures and objects in the spell's area take 10d6+30 fire and acid damage. This damage usually levels forests, crumbles mountains and causes genocides. You take this damage as well.
Upon casting, you take 8d6 necrotic damage and your hit point maximum is reduced by that amount until you complete a long rest.
You make a targeted liquid poisonous and foul. Creatures swimming in the water take 5d6 poison damage. Anyone drinking this water must succeed on a Constitution saving throw or take 5d6 poison damage.
This spell only works on bodies of water no larger than 1500 feet by 1500 feet by 150 feet.
You place a curse on the touched creature, choosing one of the following three effects:
One of their ability scores is reduced to 1.
Two of their ability scores are reduced to 5.
They have disadvantage on any d20 roll.
Each turn, they must roll a d20. On a 5 or lower, they take no action and end their turn.
Players may invent new curses, but they should be no more powerful than those listed above, and the DM has final say on the curse's effect.
A greater curse cannot be dispelled, nor can it can be removed with a break enchantment, limited wish, or remove curse spell. A miracle or wish spell removes the greater curse, and any particular greater curse can be removed if the subject performs some deed that the caster designates. The deed must be something that the subject can accomplish within one year.