You are Medium sized.

As the corruption of your body took hold, it morphed one of your arms into a hulking spike, which can be used as a weapon. This provides the added benefits and drawbacks:

Spiked Assault: You swing wildly at your target with your massive spiked arm. This attack deals 2d6 slashing damage.

ASSIMILATE: You can spend an hour melding a weapon into your arm. When doing so, it becomes automatically attuned to you (this does not count as a free attunement), and cannot be disarmed, but you lose access to the "Spiked Assault" attack.

Disarmed: You can only use weapons that are melded into your arm, have the one-handed property, and do slashing or piercing damage.

You gain the Alert feat. Additionally, you can finish a long rest in 6 hours if you spend those hours in an inactive, motionless state, during which you retain consciousness.

You leave a trail of wood, vines, and corrupt energy as you walk. You are immune to the effects of the Spike Growth spell, and you leave behind Spike Growth wherever you walk. This effect lasts a maximum of 12 seconds, or until you are incapacitated, and stretches on for a maximum of 40 feet.

Additionally, any Whisperwood that stays within 50 feet of you for at least 24 hours must make a DC 20 wisdom saving throw or become a Corrupted Whisperwood. This saving throw is repeated every hour until the target is at least 50 feet away from any Corrupted Whisperwood for an hour.

You are immune to being frightened, charmed or paralyzed, as well as automatically succeeding on attempts to escape Hold Person, Dominate Person, and Banish the turn after they have been cast.

Your size is Medium.

You gain resistance to Fire damage.

Whenever you crit, you may heal HP equal to half the damage dealt, rounded down. This may be used a number of times equal to half your proficiency bonus, rounded down, to a minimum of 1.

You critically hit upon rolling a 19 or 20. This stacks with bonuses that lower the critical hit threshold.

Your size is Large.

Your Armor Class increases by 1 and you gain the Tough feat.

Due to your durable body, you are immune to being grappled or moved against your will by entities 1 size or more smaller than you.

Red Whisperwoods can use an action to anchor themselves to the ground, preventing them from being moved against their will by any force, raising their armor class by their Constitution modifier, and healing 5% of their maximum hp (rounded down). However, they automatically fail Dexterity saving throws and have their speed reduced to 0 while in this state. You may use a bonus action to end this state. This can be used a number of times equal to your Constitution modifier.

Your size is Medium.

You gain the Resilient feat.

Your attacks inflict 1 Sinking on hit. Additionally, you gain access to a powerful attack.

Magnificent Spring Breeze

Casting time: 1 Action
Channeling petals all around the field, you unleash all the pent up sinking feelings upon your opponents. Anyone standing within 10 feet of you must make a DC 15 Charisma saving throw or take 1d4+16 Bludgeoning damage, as well as gaining 3 stacks of Sinking. (See "Sinking Deluge" for the effects of Sinking.) You may only use this attack once per long rest.

Like petals blowing in the wind, so too does sorrow sweep you away.

For each stack of Sinking on the target, they suffer a penalty of -1 on the next roll they make for each stack of Sinking they have. Then, reduce Sinking by 1.