Suppose that my AC is normally 12, and with Mage Armor it is 15. I cast Contingency, with Mage armor as the contingent spell and a trigger of "when I cast a Shield spell". Later, an attacker fires an arrow at me, rolling a 19 to hit, and I cast Shield as a reaction. Does the mage armor take effect at the same time as the shield, causing my AC to become 20 for that attack (and hence causing the attack to miss)? Or does the mage armor only take effect after the attack is finished resolving?


1 Answer 1


Mage Armor and Shield take effect before the attack

the contingent spell doesn't come into effect. Instead, it takes effect when a certain circumstance occurs. [...] The contingent spell takes effect immediately after the circumstance is met for the first time

The keyword is immediately. Because Shield interrupts the attack and the contingent Mage Armor takes effect immediately after the Shield is cast, then your AC become 20 and the attack will miss.

Therefore, here is what will happen:

  1. You are attacked
  2. You cast Shield
  3. Mage Armor takes effect
  4. Shield takes effect
  5. Attack resolves
  • 1
    \$\begingroup\$ I disagree that Mage Armor will take effect before Shield in this case, though it won't actually affect the outcome (i.e. your 3 and 4 would be swapped, but you would still get 20 AC before the attack resolves). I'm basing this off prior questions about using reactions triggered by spell casting, though Contingency isn't a reaction so alternate interpretations are still reasonable. \$\endgroup\$ Sep 4, 2018 at 19:08
  • 1
    \$\begingroup\$ @KamilDrakari actually, I'm basing my answer on how reaction works: it waits until the trigger resolves first. However, the trigger for Mage Armor is "Shield being cast", not "takes effect", thus the Mage Armor takes effect before Shield, because of the keyword immediately. \$\endgroup\$
    – Vylix
    Sep 5, 2018 at 9:34
  • \$\begingroup\$ @Vylix I don't think that's how an ordinary reaction works either. Once a spell is cast, it takes effect (unless you are holding it to release later, which isn't applicable here). There is no window of time in between the casting and effect for you (or contingency) to react in. For example, you couldn't hold a resilient sphere spell with a trigger of "when someone casts a spell at me" to protect yourself from that spell. Your reaction would happen after the incoming spell takes effect. Similarly, I don't think a contingency with the same trigger would protect you. \$\endgroup\$ Sep 5, 2018 at 20:26

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