Sigil of the Arknight (Blue)

Go again

At the beginning of your action phase, destroy this.

When this leaves the arena, reveal the top card of your deck. If it's an attack action card, put it into your hand.

Rulings

From the Rosetta + 1st Strike release notes

Sigil of the Arknight’s first ability is go again. You will only gain an action point from go again if Sigil of the Arknight resolves on the stack. If it is put into the arena by a card or an effect, you are not considered to “go again” and you will not receive the action point from it.
Sigil of the Arknight’s second ability triggers at the beginning of your action phase. Players receive priority during this phase and will have an opportunity to resolve other cards and effects before this triggered layer resolves.
Sigil of the Arknight’s third ability triggers when it leaves the arena (for example, when it is destroyed, when it is banished, etc.), even from its own effect. When the trigger resolves on the stack, you must reveal the top card of your deck. Then, if it’s an attack action card, you must put it into your hand.

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)