Arcane Channeling

You have learned to channel the essence of a spell into your melee weapon and strike your enemies with it. You can use the following methods of Arcane Channeling, choosing which one to use on your turn. Option (1) below is a valid choice to use as an opportunity attack, but only if you also have the Warcaster feat, or another feature which similarly allows you to cast a spell as an opportunity attack.

1. As an Action, you can expend a spell slot to channel the nature of one of your spells into your weapon. Choose a damage type associated with one of the spells you know, including cantrips (limited to fire, cold, lightning, thunder, or acid). Immediately afterward and as part of the same Action, you can make a number of melee weapon attacks equal to the level of the spell slot expended (maximum of 5). The damage of each of these attacks is 3d8 of the chosen damage type, and these attacks count as magical. This Action counts as casting a spell, and the magical energy dissipates from your weapon immediately after the last attack roll made as part of this Action.
2. As a Bonus Action, you cast a spell you know that has a casting time of one Action, has a duration of Instantaneous, and that has an area of effect, expending a spell slot as normal for the spell selected. Instead of the spell immediately taking effect, it is stored in your melee weapon. The next time you hit with a melee weapon attack before the start of your next turn, the effects of the spell are unleashed on the target. The spell's damage replaces that of the melee weapon damage and is not doubled on a critical hit. The target is the center of the spell's area of effect. That target may make a saving throw against the spell's secondary effects (if any) as normal, but not its damage. Any other creatures in the spell's area of effect (including you) make saving throws for the spell's damage and secondary effects as normal. If you fail to successfully land a melee weapon attack before the start of your next turn, the channeled spell is lost and you do not recover the expended spell slot.