Casting Spells normally as a standard action and off weapon attack as bonus action?

Question

RAW states that...

At least one hand is needed to cast a spell.

Light weapons can be used with two weapon fighting to gain an extra attack via a bonus action.

Crossbow Expert states you can fire a loaded hand crossbow as bonus action.

With above RAW: can you then cast a spell as a standard action and use a light off-hand weapon or fire a loaded hand crossbow as a bonus action?

I understand that Eldritch Knight can do this via War Magic and Improved Magic, but I want to know if it can be done regardless of class.

Answer 1

Nope.

• When you use the Attack action and attack with a one-handed weapon, you can use a bonus action to attack.... (PHB p.165, "Crossbow Expert," various emphases mine)

When you take the Attack action and attack with a light melee weapon... you can use a bonus action to attack.... (PHB p.195, "Two-Weapon Fighting," various emphases mine)

You didn't take the Attack action in the situation you describe, so you don't then get the bonus action granted by either Crossbow Expert or Two-Weapon Fighting.

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See also Can I cast a spell and attack in the same turn?