Season 8 Kai spell counter- to wake Elena
Kai cast a spell to make Elena remain in a comatose sleep as long as Bonnie lived. He says he booby trapped the spell so any fiddling with it or attempts to counter it would kill both of them.
We saw that bonnie could "kill" matt by stopping his heart for 6 minutes with magic and reviving him. The deed of ownership of the Salvatore house required Matt to die so Damon could enter the house again.
By that same logic then, if two witches cast a spell on Bonnie and Elena simultaneously to stop their hearts and make them both die at the same time Kai's spell should fizzle - if the booby trap in Kai's spell kicks in to kill them it can't because they'd already be dead.... then they could wait a few and be both revived by magic within 6 minutes.
What do you think