Had a question about this Card, and its first text.

It says, "When this card Would be Played..." does that mean if you reveal it with Eldradimon's effect would this mean you could play it out, or does it just apply to when you do play it?

It says, "When this card Would be Played..." does that mean if you reveal it with Eldradimon's effect would this mean you could play it out, or does it just apply to when you do play it?