Barrier

Create a magical barrier with in range that is 5ft by 5ft by 1ft. Alternatively create a maximum 5ft radius sphere centered on you. The barrier has an AC equal to your spell save DC and 2d12 HP regardless of which option you have chosen. The barrier is treated as an inanimate wall for saving throws. The acts as a wall and is normally see through like glass, thus granting full cover but not stopping line of sight spells with no projectiles like charm person or charm monster. The barrier lasts until it is broken or you use a free action to dispel it. 

Alternatively you make cast this spell as a reaction to a ranged attack, spell or ability targeting you or your allies. When used this way the duration is changed until the start of your next turn (it still ends if broken or dispelled as a free action).

At Higher Levels: Each level beyond first increases the dimensions by 5ft(2nd level would be 10ftx10ftx1ft) each 5ftx5ft section has it's own health bar, increases the HP of the barrier by 1d12, and increases the maximum radius of the sphere by 5ft, you may decrease the radius on cast to be less than the maximum. Alternatively you may add one of the following properties to the barrier instead of increasing dimensions, HP, or Radius for that level. (if you have the levels available to skip you may add more than one option, but not more of the same option).

Physical resistance: Resistance to Bludgeoning, piercing, and slashing damage.

Magic resistance: Resistance to damage from spells and magical abilities.

Element resistance: Resistance to damage for natural but not magical sources besides weapons. (breath weapons, Molotov's, weather, running water are all examples)

Thorns: When hit with a melee attack and withstood the damage deal 1d12 magical piercing damage.

Spell reflection: When hit with a single target spell or ability and withstood damage reflect the spell at half damage (still roll for attack and saving throws) .

Illusion: The barrier takes on an illusory appearance of your choice. It only extends the exact dimensions of the barrier and does not generate light, heat, or other affects, you may alternatively cause the barrier to be fully invisible.

Self-repair: As long as the barrier has HP it regenerates at a rate of 1 HP per round, as long as 1 section of barrier remains the section directly attached to it will begin regenerating after 1 minute of the remaining barrier having full HP.

Dispel Defense: Once per day the barrier defends itself against one instance of dispel magic or similar dispelling effects. The dispel magic or dispelling effect are treated as being countered or succeeding a saving throw against the effect. The casters may succeed an Arcana check against the caster's spell DC to know that this effect was a once a day effect.

Other options may be available at DM's discretion.