This old Tome contains long forgotten Knowledge of the Abjuration School of Magic.

Enhanced Arcane Ward
Your Arcane Ward gains additional max HP equal to your Proficiency Modifier.
Once per short Rest when your Arcane Ward is broken, it explodes and deals damage equal to your intelligence modifier to the creature that broke it and forces a Con-Save equal to your Spellcasting DC.
On a succesful save the target has disadvantage on attack roles until the start of its next turn, on a failed save the target has disadvantage on attack roles until the start of its next turn and is stuned for one Round.

Help a Friend
When you use your Projected Ward, until the start of their next turn the target gains a +5 bonus to AC, including against the triggering attack, and takes no damage from magic missile.

Notes: by a School of Abjuration Wizard.