Invoke Cromai (Red)

Transform target ash you control into Cromai. Go again

The dragon of engineering, said to soar over the Metrix rust belt.

Rulings

From the Uprising release notes

“When this attacks” is a triggered effect that triggers when the dragon is considered to have attacked, during the attack step. It does not trigger if the combat chain closes in the layer step of combat. After it triggers, it will still resolve even if the dragon ceases to exist or the combat chain closes.
This triggered effect triggers when Cromai ceases to exist (such as when it flipped back to an invocation) or otherwise leaves the arena.
This triggered effect only triggers once per turn. If Cromai attacks and then leaves the arena later in that turn (e.g. from phatasm), you would still only gain 1 action point in total.
Gaining an action point from the triggered effect is independent of gaining an action point from go again. If Cromai also has go again, you would gain net 1 action point after attacking with it.

Keyword notes

Transform - Put the X under this/it/him/her

Create a Y and put the X under it.

Transform is a discrete effect.
To transform subject objects into a specified object, first create the specified object in the arena if it does not yet exist, then put the subjects under it.
To transform objects into a token that does not exist yet, first create the token, then put the objects underneath it.
To transform objects into an existing permanent, just put the objects underneath it.
When used in conjunction with cards that flip (e.g. Invocations), the card is first flipped and becomes a permanent in the arena, then the transform will refer to that permanent as the specified object to transform into (the permanent to put cards under).
The transform fails if there are no transform subjects, or if they can not be put under the specified object for whatever reason.

All keywords

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)