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Oh gods, my players would use the Spell Burst ability for any and all concentration spells

LOOK! I know what you're thinking, and yes, this thing is ridiculous. Give to your players at your own RISK! But the Twitch Chat wanted a Book Bomb, so they got a Book Bomb.
Spellbook Bomb
Wondrous Item, legendary (requires attunement)
“A unique spellbook that absorbs spells cast into it. The arcane runes and gems on the front cover glow and pulse as more power is transferred into its pages. When at full capacity, it’s a deadly magic item regardless of the hands that hold it.”
This magic spellbook can store up to 12 levels worth of spells at a time. Any creature can cast a spell into the spellbook by touching it as the spell is cast. The spell has no effect, other than to be stored in the spellbook. If the spellbook can't hold the spell, the spell is expended without effect. The level of the slot used to cast the spell determines how much space it uses.
Book Bomb. As an action you can throw this spellbook into a space you can see within 30 feet and speak the command word. Any creature within 20 feet of the book must make a Dexterity saving throw or take 2d6 damage per level of spells stored in the book, or half as much on a success. You can choose the damage type from one of the spells stored in the spellbook. This does not destroy the spellbook. The spellbook is emptied of all spell levels following this action and you cannot store spells in it for 24 hours.
Spell Burst. When detonating the spellbook you can instead choose to unleash all of the spells stored inside at the same time. Any creature within range of a spell is subject to the effects. A spell with a single target is determined at random, so long as all other prerequisites of the spell are met. Touch spells affect a random creature within 20 feet of the spellbook. The spell uses the slot level, spell save DC, spell attack bonus, and spellcasting ability of the original caster, but is otherwise treated as if you cast the spell. Spells that require concentration, do not, lasting their full duration. The spells cast from the book are done so in a random order, and are no longer stored in it. After using this action, roll a d20, on a result of 1-5, the book is destroyed. Otherwise you cannot store spells within it for 7 days.
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