[RPG] Can a spell be cast while using a bonus action to control another spell

actionsdnd-5espells

Spells such as the cleric's Spiritual Weapon and the Wizard's Bigby's Hand enable the caster to continue to manipulate the spell's effect as a bonus action after the spell has initially been cast.

Separately, page 203 of the player's handbook states:

Bonus Action
A spell cast with a bonus action is especially swift. You
must use a bonus action on your turn to cast the spell,
provided that you haven’t already taken a bonus action
this turn. You can’t cast another spell during the same
turn, except for a cantrip with a casting time of 1 action.

Hence my question is does this prohibition apply only to the initial turn on which such a spell is cast, or to all subsequent turns on which the effect is manipulated as well? Put more fully, after casting a spell with a continuing effect manipulated via their bonus action, can a caster use their action to cast a spell (beyond a cantrip) whilst also using their bonus action to manipulate the continuing effect?

Best Answer

Controlling a spell is not casting it

On the first turn, you are right, you can cast Spiritual Weapon (as a bonus action) and a Cantrip (as an action) but not any other spell.

On the subsequent turns you can cast any spell as an action and then use your bonus action to control an already existing spell. In fact, you can have both active and control one of them using your bonus action, while the other one is on standby and still cast another spell.

Note, that Bigby's Hand duration is based on Concentration. This means you will not be able to cast any other Concentration spells if you want to keep Bigby's Hand active at the same time. Spiritual Weapon does not suffer from it.