Snake Assurance

Snake Assurance (スネーク保証 Sunēku hoshō) is a spell that is distinct to the Snake Trap guild, specifically the Guild Master herself, Inke.

Description
Snake Assurance is essential a safety spell. It was developed by Inke who wanted a way to keep Snake Trap members from communicating about the guild. Thus, Snake Assurance was born. Unknown to most, Snake Assurance is imprinted in the wearer's guild insignia when they first receive it.

To activate, Inke gives them a specific set of rules they cannot break, otherwise they will face "dire consequences". If one breaks a rule, their guild mark glows a bright red and grows extremely hot, causing discomfort and pain. After a few seconds, the guild mark doesn't return to its original color, but instead, it disappears along with the pain.

This was the undetectable poison being released into their system. The poison causes no apparent pain.. The user simply falls unconscious and within minutes, their heart stops. The poison is special because it uses the user's own magical power against them. It causes their own magical power to gently squeeze their heart harder than the average human is able to withstand.

Unless Inke has a change of heart (which is rare), or the victim receives immediate medical assistance, they are pretty much gone.

When Snake Assurance is activated, Inke receives a mental note about who it is and what rule they broke.

Trivia

 * This spell took Inke years to develop and perfect.