Amulet of Havencall (Blue)

Go again

Defense Reaction - Destroy this: Search your deck for a Rally the Rearguard, add it to this chain link as a defending card, then shuffle. Activate this only if you have no cards in hand.

Rulings

From the Everfest release notes

Amulet of Havencall’s activated ability is a defence reaction. You can only activate Amulet of Havencall during the reaction window when you are the defending hero.
You cannot defend with Amulet of Havencall as it has no defense property. (This is different than if it had a defense value of 0.)
You can fail to find Rally the Rearguard in your deck. Even if your deck does not contain a Rally the Rearguard, or it contains a Rally the Rearguard but you fail to find it, you must still shuffle your deck.
Adding Rally the Rearguard as a defending card to the chain link is considered defending.
“This chain link” refers to the current chain link of the combat chain.

Keyword notes

Go again - Go again allows multiple actions to be played in a turn when usually playing an action with use up your action point, and therefore end your turn. A card with go again gives the controller of that card or activated ability 1 action point when it resolves.

When an action with go again resolves, its controller gains 1 action point.
Multiple instances of go again on the same card or activated ability do not stack. If a card or activated ability has multiple instances of go again when it resolves its controller gains 1 action point only.
If an action with go again does not resolve, its controller does not gain 1 action point.
You cannot reveal a card with no to Belittle. The card must have a value to its power that is 3 or less. (0 is a value)