pokemon cards etb TCG: Mega Evolution Elite Trainer Box – AllPokeTCG flip die Crystal TCG – Colored Acrylic

Cube is the only format where the designer has complete control over the card pool, up to and including cards that arent powerful enough to be impactful in other formats

Physical cards were likely used to show potential toy market buyers & store chains of the potential

But again, the key point is that these are priced all over the place depending on where you look

While this card sadly doesnt ping whenever a creature enters on your side of the battlefield, getting this trigger on casts is nearly as good, and it will surely aid you in filling up your hand with more threats so you can employ all that mana, which Elves are so good at producing

My .02 is just a quick take