Can a level 20 Samurai fighter with the True Strike cantrip make 9 attacks in a turn, all with advantage?

Question

The true strike cantrip can be cast as an action to grant yourself advantage on the first attack roll against the target on your next turn.

The Samurai fighter's Fighting Spirit feature description says (XGtE, p. 31):

As a bonus action on your turn, you can give yourself advantage on weapon attack rolls until the end of the current turn.

The Rapid Strike feature description says (emphasis mine):

If you take the Attack action on your turn and have advantage on an attack roll against one of the targets, you can forgo the advantage for that roll to make an additional weapon attack against that target, as part of the same action. You can do so no more than once per turn.

Say I have a level 20 Samurai fighter, and I've taken the Magic Initiate feat to learn the true strike cantrip. Can I cast true strike on turn 1, then on turn 2, use the Rapid Strike feature to turn it into 2 attacks, giving me 5 regular attacks + 4 more from Action Surge, then use my bonus action to use Fighting Spirit?

Are all 9 attacks all at advantage? The description of Rapid Strike says "if you take the Attack action on your turn". As it doesn't specify when on your turn you're doing it, is it allowed to then give the attack advantage again?

Answer 1

No, you either get an additional attack or advantage on the first roll

If you use Fighting Spirit before taking your first Attack action, your first attack would have advantage applied from two sources. But advantage and disadvantage don't stack. That is, you can't have "double advantage."

If multiple situations affect a roll and each one grants advantage or imposes disadvantage on it, you don't roll more than one additional d20. If two favorable situations grant advantage, for example, you still roll only one additional d20.

So by using Fighting Spirit, your first attack (along with all your other attacks) gains advantage, which it already had from True Strike. Once you decide to take a second attack instead of advantage, the advantage is foregone as a form of payment to activate that ability.

Best case, all attacks except the first one would have advantage (the second attack created by Rapid Strike would benefit from Fighting Spirit).

As for timing, you can't give advantage to attacks that have already been made. So you can't use Fighting Spirit after the attacks you want it to apply to. You have to use it first. But this is not a problem because you can simply take your bonus action before your other actions. This would make True Strike unnecessary (even wasteful).

Answer 2

No, this doesn't work.

The reason why has nothing to do with "double advantage", like some of the answers here claim, since your proposed process involves gaining advantage, losing advantage, and then gaining it again; at no point do you actually have Advantage twice.

Instead, it's because there's no time between choosing to activate Rapid Strike and the resolution of the attack to activate Fighting Spirit to regain advantage on that attack.

Like you quoted in the Question, Rapid Strike says the following:

Rapid strike ... if you take an attack action on your turn and have advantage on an attack roll against one of the targets, you can forgo the advantage for that roll to make an additional weapon attack against the target, as part of the same action. You can do so no more than once per turn.

So, when you're making the attack roll, you can choose to lose the advantage to make an extra attack roll as part of the same Action.

Answer 3

Only the first attack is at advantage.

The description of the spell True Strike states (PHB, page 284; emphasis mine):

On your next turn, you gain advantage on your first attack roll against the target, provided that this spell hasn't ended.

As such, only the first attack will have advantage, and any afterwards would not. This is because attacks are separate from Actions.

Answer 4

By RAW, all 9 attacks get advantage

First, lets establish that the rules do what they say they do, and there are no secret rules.

The Rules for Advantage say:

If multiple situations affect a roll and each one grants advantage or imposes disadvantage on it, you don't roll more than one additional d20.

If you have advantage from 2 sources, you do not roll bonus 2d20. However, the rules do not say that you do not actually have advantage twice. If an effect such as Rapid Strike removes advantage, I would read it as removing only 1 advantage.

Most people (including me) think that the designer's intent was that at the time you make the attack, you either have advantage, or you don't. But the rules only cover how to roll the die when you have multiple or a mix of advantage/disadvantage.

I am not aware of the rules ever saying that having advantage from multiple sources means you only have advantage once, only that you only roll 1 bonus d20.

The wording of Rapid Strike is "you can forgo the advantage for that roll" The determiner "the" isn't explicitly plural, and "advantage" isn't plural either. There is no possible reading of "the advantage" to nullify multiple sources of advantage, and there is no way that a native English speaker would think otherwise. It would be easy for the author to say "all advantage" or "is made without advantage". But they didn't, they said "the advantage". By RAW, there is no other way to interpret this.