The Grimoire

You made a pact with an elder sentient and powerfull grimoire. This grimoire can give you arcane power  and knowledge. But it normally wants you to travel, meet new things and write more spells in it.

Grimoire defense

Your Grimoire is thirsty for arcane power and knowledge, allowing you to ask him to intervene and absorb enemies spell power. At level 1 When you can see an allie being target by a spell that makes an attack roll or saving throw, you can spend a reaction to give your charisma modifier as AC or bonus in the saving throw for the target. If the spell's atack roll misses or if the target succed in the saving throw, the grimoire absorves arcane power from the spell gaining a spell slot equal to half that spell level rounded up and from the class of that caster that casted that spell. this spell slot can only be used to cast  spells from its class spell list.

Grimoire Learning ritual

Your Grimoire can absorca arcane force directly from spells and scribe then in itself. On level 1.  You can learn your oponents spells. When you use your grimoire defense to try and stop a spell and you succeed, you can use spend a bonus action on your next turn and a spell slot to learn that spell permanently as a warlock spell and a spell of the original spellcasting class of the spellcaster you learned from. You can only do this with spells on a level that you already can learn and cantrips. those spells dont count for the amount of spells you know for your class.

Ignorance Destroyer

When people say that knowledge give you wings, you never thought it would be so literal. Starting at level 6, you can use your bonus action to make your grimoire grow in size and then hop onto it for ten minutes. While onto your grimoire, you gain a flying speed equal your walk speed, can cast eldritch blast from your grimoire as a bonus action. Your AC becomes 10+Inteligence modifier+ charisma modifier. And you can chose to change each individual eldritch blast attack damage type to any damge type from a known spell.

Knowledge Embodiment

You rip part of the knowledge of the grimoire, materializing its knowledge into a tangible creature. At level 10, as a bonus action you can spend a spell slot and summon a creature made of magical letters written in midair. The gliph creature has the same stat block  and shape as a creature of a CR equal to your Charisma modifier. Extra temporary hit points equal to a number of d6 equal to your wisdom modifier(min 0) Extra AC equal to your inteligence modifier and extra damage in any attack equal to spent spell slot level. This summon remmains for one hour if not destroyed or until you re-use it. This creature moves at its own initiative and turn, but you completely controls it.This gliph creature is weak to force damage

Knowledge Monopoly

When you see a creature casting spells you know, you can have your grimoire absorbing that arcane power, to simantle the magic from even happening. At level 14. Whenever you can see an enemie cast a spell that you know, you can use your reaction to spend a slot of the same level of that spell and the creature's spell fails and has no effect.