A 40' tall shadowy tree instantly spring forth from the ground from a point within range and attempts to grapple any creature within a 20' range using the spell caster's Spell DC instead of Strength.  Once one creature is grappled, the shadowy tree will not grapple another that victim is freed or the spell ends.  Concentration is not required.The caster can only have one version of this spell active at one time. If a second attempt to cast this spell is made while another is active, both spells fail, both spell slots are spent and the victim is release without further harm.

The unfortunate grappled creature now becomes a hit point sink for the caster.  Any damage damage done to the caster, half (rounded down) will be transfer to the capture creature.  Thus the caster takes half damage from any hit. The captured creature will be release if one of the following conditions are met:

1. The captured creatures hit points are reduced to zero
2. The captured creature successfully escapes the grapple
3. The spell is dismissed by the caster
4. The caster dies
5. The Shadowy Tree takes damage equal to the casters Spell DC - unfortunately for the captured creature, it also take the same damage
6. After the spell dissipates 24hrs later

If the creature is released under conditions 1 or 2 above, the Shadowy Tree will continue to grapple any creature to gets near until the spell dissipates. 

Note: the Shadowy Tree will not do any harm to the captured creature unless the caster or itself takes damage.  The captured creature is even able to be healed, fed, rest, etc. while held.