Sometimes after a powerful xmp explosion an attacked portal drops its own keys.

What determines whether a portal will drop its key as a result of an xmp blast (and how many keys will be dropped)?

Today's observation: L6 xmp explosion near L1.5 portal caused the portal to drop 3 keys, 6 of 7 resonators were destroyed at once.

2 Answers 2


AFAIK, destroying resonators at linked portals will sometimes cause a portal key to the remote end to drop.

  • Interesting, so this is not only target portal keys. Dec 21, 2012 at 21:00

The link between two portals holds if three or more resonators stand.

Once any of the last three resonators gets destroyed, all links anchoring at the particular portal will be destroyed and the keys used to build them will be dropped at a portal used to link from.

from       to
A -------> B

Here in this scenario, someone at portal A used key b to link from A to B.
If the link is destroyed, by attacking A or B, the key b will appear at portal A.

  • 1
    Keys don't appear "only" at the originating Portal when the link is destroyed. They can appear the targeting Portal, too. And secondly there isn't a certainty that keys will be dropped when a link is destroyed. The point of the key drop and the key dropping are random events based on chance.
    – Montag451
    Aug 1, 2014 at 17:09

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