Edeneth's Logic Knot

You send a spike of dunamis into the brain of the target spellcaster in range just as they are in the midst of casting, which briefly overloads their synapses with conflicting mnemonic information from both their past and their yet-unrealized possible futures at random, forcing them to make an intelligence saving throw. On a failure, the target's spell fails and the slot used is wasted, the targets takes 3d8 psychic damage, and the target has disadvantage on their next spell attack while targets of their spells have advantage on savings throws against their spells until the end of the target's next turn.