Word as Bond

When you cast this spell, you spend the casting time drawing an arcane seal using the material components. The seal describes any conditions that you desire that two target willing creatures must agree on.

The seal must be pressed between those two creatures, as with a handshake, within a minute of it's writing or the spell fails. When that happens the parchment burns up leaving a faint marking of the seal on both creatures.

The seal is clearly visible to creatures with truesight or creatures affected by See Invisibility or a similar spell. A creature that knows this spell can decipher the seal's conditions. Casting Identify on the seal or the creature reveals the conditions as well.

While each creature is affected by this spell, the seal is capable of doing two things depending on if the conditions are met or broken. If the conditions are broken, the seal can deal necrotic damage equal to both cretures' health added together to either creature, divided however the conditions stipulate. This damage cannot be negated or transferred by some other spell. If the conditions are met, the seal can end the spell releasing both creatures from the agreement. The spell ends if either creature dies.

The spell is considered a curse for the purposes of removing it, and can only be removed by spells of 6th level or higher.