Mark of Sarius- (requires minimum warlock lv12)

This eldritch mark binds to the warlocks pact boon allowing them to store spells once per short rest similar to a ring of spell storing. 

The level of spells able to be stored is equal to the proficiency bonus plus their charisma modifier and the spell may be stored as either the available level of the pact slot or the base level of the spell.

Pact of the blade: The warlock may only store spells with a casting range of self. When the user makes a weapon attack using their pact weapon they may sacrifice a stored spell to use eldritch smite matching the level of the spell sacrificed.

Pact of the chain: The warlock may only store healing spells and spells of the illusion school. The familiar may cast these spells using the warlock's modifier.

Pact of the talisman: The warlock may store any spell but may not use them. The wearer of the talisman may cast stored spells, when the wearer casts any spell stored in the talisman within 60ft of the warlock the warlock may use a reaction to cast the same spell of the same level at no cost.

Pact of the tome: The warlock may only store ritual spells and spells of the evocation school. If the warlock has a spell book containing recorded spells or a spell scroll the warlock may complete an hour long ritual to store this spell in their book of shadows, this will destroy the page/scroll originally containing the spell. Alternatively the warlock may complete an eight hour ritual followed by an arcana check (DC 15 + spell level) to permanently add the spell to their book of shadows that may be cast once per long rest. (Failure or an interruption of the ritual will destroy the original spell)