Arcane Focus of Abjuration

When this arcane focus is attuned by a wizard from the abjuration school of magic, it allows any spell of the abjuration school cast through this focus to be cast as though a spell slot of one level higher had been expended in its casting.  For example, if a wizard casts a 3rd level abjuration spell using a 3rd level slot, it will take effect as though the wizard has expended a slot of 4th level instead, if that spell has any higher level abilities.

Notes: by a Wizard of the Abjuration school, Buff