Touch a creature with a seed. Roots and vines hatch from the seed, immidiately growing around and through the creature's body dealing 10d6 piercing damage and inflicting one level of exhaustion due to extreme pain. Roots and vines complitely envelop the creature into what rapidly became a tree, rendering the creature paralyzed and immune to damage coming from any source other than this spell for its duration.

Each round (up to 6) you mantain concentration on this spell, the tree grows, producing additional effects on your turn. Each turn after the first (up to 6) the creature makes a Wisdom saving throw. On a successful save the creature only takes half damage, no additional effects of that turn and frees from the spell, losing its forementioned immunity.

Round 2. The tree grows up to 20 feet with a diameter of 5 feet. Roots pierce deeper and tighten onto the creature's body dealing 2d6 force damage and applying a second level of exhaustion.

Round 3. The tree grows up to 50 feet with a diameter of 10 feet. The creature takes again 2d6 force damage. As the tree grows, the vines shift and twirl dealing 3d6 slashing damage and applying a third level of exhaustion.

Round 4. The tree grows up to 100 feet with a diameter of 15 feet. The creature takes again 2d6 force damage and 3d6 slashing damage. The roots piercing the creature absorb its life essence dealing 4d6 necrotic damage and applying a forth level of exhaustion.

Round 5. The tree grows up to 240 feet with a diameter of 30 feet. The creature takes again 2d6 force damage, 3d6 slashing damage and 4d6 necrotic damage. The creature is pushed on the verge of madness from the pain and takes 5d6 psychic damage, becoming vulnerable to psychic damage for the next 7 days (does not affect this turn's damage) and suffering a fifth level of exhaustion.

Round 6. The tree grows up to 500 feet with a diameter of 60 feet. The creature takes again 2d6 force damage, 3d6 slashing damage and 4d6 necrotic damage. It also takes 10d6 psychic damage and suffers an ultimate level of exhaustion, though the tree sustains the creature, making it unable to reach unconsciousness or to drop below 1 hp. Its vulnerability to psychic damage is now permanent. The spell doesn't require concentration anymore.

Subsequent rounds. The tree grows one last time up to 1000 feet and 100 feet of diameter. The creature takes 10 piercing damage, 10 force damage, 10 slashing damage, 10 necrotic damage and 60 psychic damage per turn. It can't make anymore saving throws and will remain confined in an impenetrable prison of everlasting agony and madness, unable to savor the peace of death.

If Dispell Magic is casted on the tree,  its wood becomes destructible by normal means, but the creature is no longer kept alive by the spell and dies.