Bequeath Unto Them

Giveth unto them as they taketh from you.

Banish one creature one size class larger to the Feywild at your expense. 

Roll 1d20 and add your constitution modifier. Target must successfully dispel your roll with 1d20 + their Charisma modifier. 

For every roll they succeed, you can choose to take 2 damage to prevent their escape, increasing in 1 damage increments every time you choose to prevent the escape. If you go below 5 health, they escape automatically.