Base Class: Ranger
A Master of Beasts forms a mystical bond with a special animal, drawing on primal magic and a deep connection to the natural world.
This is a modified and improved version of the Beast Master subclass found in the Player's Handbook, meant to improve both the Primal Companion beast and your Action Economy. I have also posted modified and improved versions of the Stat Blocks for Beast of the Land, Beast of the Sea, and Beast of the Sky.
Level 3: Primal Companion
You magically summon a primal beast, which draws strength from your bond with nature. Choose its stat block: Beast of the Land, Beast of the Sea, or Beast of the Sky. You also determine the kind of animal it is, choosing a kind appropriate for the stat block. Whatever beast you choose, it bears primal markings indicating its supernatural origin.
The beast is friendly to you and your allies and obeys your verbal commands. If you issue multiple verbal commands, it only obeys your most recent command. It vanishes if you die.
The Beast in Combat. In combat, the beast shares your Initiative count, but it takes its turn immediately after yours. It obeys your verbal commands (no action required by you). If you don’t issue any, it takes the Dodge action and uses its movement to avoid danger.
Restoring the Beast. If the beast has died within the last hour, you can take a Magic action to touch it and expend a spell slot. The beast returns to life after 1 minute with all its Hit Points restored and in prime physical condition, instantly regenerating any missing body parts or limbs.
Replacing the Beast. Whenever you finish a Long Rest, you can summon a different primal beast, which appears in an unoccupied space within 5 feet of you. You choose its stat block and appearance. If you already have a beast from this feature, the old one vanishes when the new one appears.
Level 7: Exceptional Training
Whenever you issue a verbal command to your Primal Companion beast to take an action, you can also take a Bonus Action to command it to take the Dash, Disengage, Dodge, or Help action using its Bonus Action.
In addition, whenever it hits with an attack roll and deals damage, it can deal your choice of Force damage or its normal damage type.
Level 11: Bestial Fury
When you command your Primal Companion beast to take the Beast's Strike action, the beast can use it twice.
In addition, the first time each turn it hits a creature under the effect of your Hunter's Mark spell, the beast deals extra Force damage equal to the bonus damage of that spell.
Level 15: Share Spells
When you cast a spell targeting yourself, you can also affect your Primal Companion beast with the spell if the beast is within 30 feet of you. When you cast a spell with a range of touch, your Primal Companion beast can deliver the spell as if it had cast the spell. Your Primal Companion beast must be within 100 feet of you, and it must use its reaction to deliver the spell when you cast it. If the spell requires an attack roll, you use your attack modifier for the roll.