Can a multiclass Beastmaster/Wizard benefit from using Speak with Animals to cast Suggestion on their own animal companion?

Question

As a Beastmaster 3 / Wizard 3, I want to use Speak with Animals to enable my using the Suggestion spell on my beast companion, for the purpose of issuing to her a two-sentence set of "marching orders".

My motivation is so that I don't have to use up my Action each round just to have the beast repeat the Attack or Help action when there is a consistent, repetitive pattern of actions I desire.

A couple of illustrative cases for my intended use of Suggestion with my animal companion are:

1. "Doggedly attack anyone not in our group who enters this clearing. But if you get badly hurt, disengage and hide."

2. "Flank whomever I'm attacking and distract them, to help my attacks. But if you get badly hurt, disengage and move behind me."

Will these sorts of applications of Suggestion work for me, in principle, with my own bonded beast companion, according to the rules-as-written? (And if so, can my bonded animal companion automatically fail its save for Suggestion?)

Answer 1

Yes, but...

According to the spell description, the Suggestion spell has three requirements that need to be fulfilled.

1. It must target a creature.
2. The targeted creature must be able to hear and understand you.
3. The suggested course of action must be worded in a manner to make it sound reasonable.

Because Speak With Animals grants you the ability to understand and be understood by beasts, it allows you to fulfill the second requirement for Suggestion. Assuming your suggested course of action is reasonable, the beast would be a valid target for suggestion.

However, the use you specified would not work the way you want it to:

PHB, 93

The beast obeys your commands as best as it can. It takes its turn on your initiative, though it doesn’t take an action unless you command it to. On your turn, you can verbally command the beast where to move (no action required by you). You can use your action to verbally command it to take the Attack, Dash, Disengage, Dodge, or Help action.

You are required to use an action to control your beast. It's basically an extension of yourself, and Suggestion would not count as a command for the purpose of controlling your companion in-combat.

Answer 2

No

The beastmaster ranger subclass description says, in part:

It takes its turn on your initiative, though it doesn't take an action unless you command it to

There is no way around this. The animal never takes any action you don't command it to if it has any volition in the matter. This is the fundamental problem with the beastmaster subclass and why you are better off grabbing an animal from the forest and making friends than ever using the one you get from your class feature.

Use the fixed class instead

Because of the underlying fundamental brokenness of the beastmaster subclass, Wizard's has publicly apologized for the lack of quality and made available a fix¹ in the form of the Revised Ranger. The 'beast conclave' ranger, while still very weak, is much, much better than the PHB beastmaster and no longer has the action restrictions present in the original yet for no other companion creature in the game.

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1. Technically, there were two fixes, the revised ranger being the second of the two. The first was even worse than the PHB ranger in terms of playability, though it was at least less entirely impotent.