Shield is the classic “I would rather not die this turn” reaction. For the cost of a 1st-level slot, you gain +5 AC until the start of your next turn — and you take no damage from Magic Missile.
This Shield 5E guide covers the timing, what it does and does not stop, and when to save the slot.
- Spell Level
- 1st
- Spell Type
- Abjuration
- Casting Time
- 1 Reaction (when you are hit by an attack or targeted by Magic Missile)
- Range
- Self
- Component Requirements
- Verbal, Somatic
- Duration
- 1 round (until the start of your next turn)
- Class
- Sorcerer, Wizard (and several subclasses / features)
How does Shield work?
You cast Shield as a reaction when:
- You are hit by an attack, or
- You are targeted by Magic Missile
Until the start of your next turn, you have a +5 bonus to AC, including against the triggering attack. That often turns a hit into a miss after the roll is already announced.
You also take no damage from Magic Missile for the duration.
Best times to cast Shield
The attack that would drop you
If you are low HP and an attack connects, Shield is frequently the correct reaction — especially before you have access to stronger defenses.
Magic Missile volleys
Force damage from Magic Missile ignores cover and many resistances. Shield is one of the cleanest hard counters in the game.
Against multiattack
+5 AC lasts until the start of your next turn, so it can spoil several attacks from the same creature (or several creatures) in that window.
When not to cast Shield
- The hit is trivial chip damage and you need the reaction for Counterspell.
- You already have a huge AC buffer and the attack barely connected on a natural 20 (Shield does not cancel critical hits by itself — it can still make the attack miss if +5 AC pushes you out of range before crit confirmation rules at your table; most tables resolve hit/miss first).
- You are about to take a save-based fireball and Absorb Elements is the better reaction.
Shield vs other reactions
| Option | Slot | Stops |
|---|---|---|
| Shield | 1st | Attacks / Magic Missile via AC |
| Absorb Elements | 1st | Elemental damage on a save/hit that deals energy damage |
| Counterspell | 3rd+ | Spells being cast |
| Hellish Rebuke | 1st | Punishes a hit with fire damage (does not prevent the hit) |
Many blaster casters prepare both Shield and Absorb Elements. Warlocks who pick Armor of Agathys still love Shield because temp HP and AC stack in different ways.
Frequently Asked Questions
Does Shield work against saving-throw spells?
No. Fireball, Lightning Bolt, and similar save spells are not attacks and are not Magic Missile. Use cover, Evasion-like features, or Absorb Elements instead.
Can you Shield after you hear the damage number?
Usually you react when you are hit — before damage is applied. Your DM should give you the chance to declare Shield when the hit is announced.
Does Shield stack with mage armor or heavy armor?
Yes. Shield is a bonus to AC, so it stacks with whatever your AC calculation already is (within normal bonus stacking — it is not a second base calculation).
