You surround yourself in an invisible aura of protective magical energy that negates and absorbs spells that target you, allowing you to use that arcane energy to fuel your own spells. Whenever you are targeted by a spell that you did not cast, that spell fails and has no effect. A spell with multiple targets is negated for all targets, but an area of effect spell without specified targets can still affect you normally.

Whenever a spell or a cantrip is negated by this spell, you absorb a number of spell levels equal to the level of the spell negated. You can absorb and store up to 30 spell levels, at which point spells that target you are no longer negated, and no additional spell levels can be stored.

If you are targeted by a spell whose level exceeds the remaining storage capacity of this spell, the spell that targets you is not negated. Instead, you absorb and store a number of spell levels up to the maximum allowed, you have resistance to any damage from the spell that targets you, and if the spell that targets you allows a saving throw you make it an advantage. 

As a bonus action, you may convert any number of spell levels stored into a spell slot of that same level. (1 spell level equals 1 spell slot 1, 2 spell levels equal 1 Spell Slot 2, or 2 Spell Slot 1)

At any time, you can choose to suppress the negating effect of this spell until the start of your next turn (no action required).