You have learned how to infuse your weapon with a spell and deliver that spell through an attack.
When you hit a creature with a melee weapon attack, you can use your reaction to cast a spell you can cast with a range of "touch" and a casting time of 1 action or 1 bonus action (like shocking grasp, inflict wounds, or bestow curse), targeting the creature you attacked. The creature also takes damage from your weapon attack as normal.
If the attack is a critical hit and the spell deals damage, you can roll the damage dice for your spell twice just as you would for the weapon's damage dice.
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