The wolf has advantage on Wisdom (Perception) checks that rely on hearing or smell.

The wolf has advantage on an attack roll against a creature if at least one of the wolf's allies is within 5 feet of the creature and the ally isn't incapacitated.

Nonmagical snow and ice don't cost the wolf additional movement.

The wolf has advantage on Wisdom (Survival) checks made to track creatures across snow or ice.

The wolf's thick coat has become exceptionally resistant to the frozen environment.

The wolf has advantage on saving throws made to avoid being knocked prone.

Snowstorms no longer overwhelm the wolf's powerful senses.

The wolf has advantage on Wisdom (Perception) checks relying on hearing or smell during heavy snowfall or blizzards, and nonmagical snowfall doesn't impose disadvantage on those checks.

The wolf's connection to its allies has strengthened. When an ally is within 5 feet of the wolf's target, the wolf's first successful Bite against that creature on its turn deals an additional 1d6 damage. This retains normal Pack Tactics while giving it a modest higher-level improvement.

The wolf's connection to its allies has strengthened. When an ally is within 5 feet of the wolf's target, the wolf's first successful Bite against that creature on its turn deals an additional 1d6 damage. This retains normal Pack Tactics while giving it a modest higher-level improvement.

The wolf's connection to its allies has strengthened. When an ally is within 5 feet of the wolf's target, the wolf's first successful Bite against that creature on its turn deals an additional 1d6 damage. This retains normal Pack Tactics while giving it a modest higher-level improvement.

The wolf has become extraordinarily difficult to overwhelm.

When the wolf takes cold damage, in addition to its resistance, it can use its reaction to gain temporary hit points equal to its proficiency bonus.

It can do this a number of times equal to its proficiency bonus per long rest.

Once on each of its turns, when the wolf takes the Dash action, it can move an additional 20 feet.

During this movement, nonmagical difficult terrain doesn't cost additional movement.

The wolf instinctively protects its pack.

When an ally within 10 feet of the wolf makes a Dexterity or Wisdom saving throw, the wolf can use its reaction to grant that creature advantage on the saving throw.

The wolf can use this ability a number of times equal to its proficiency bonus per long rest.

At Level 20, the wolf has become a legendary example of its species.

It gains all of the following:

🐾 Unstoppable Hunter. Its walking speed increases by 10 feet.

❄️ Child of Winter. The wolf becomes immune to cold damage instead of resistant.

🐺 Legendary Pack. Once per turn when the wolf hits a creature while benefiting from Pack Tactics, it deals an additional 2d6 damage instead of the 1d6 from Greater Pack Tactics.

🌨️ Born of the Tundra. Nonmagical difficult terrain caused by natural environments no longer costs the wolf additional movement.

This progression also means her species doesn't depend on being a Bard. If another player later chooses a Tundra Wolf Fighter, Cleric, Rogue, etc., you can give them this exact same species progression and then layer their chosen class on top.