Batadon

See title, for example [[Generous Patron]]. It's a long running question I had with a friend, and we kind of came to the conclusion that the answer is no because the creature doesn't yet exist when the ETB resolves.

But I gave it some thought again because it feels so weird that so many cards have this kind of effect and supposedly it doesn't get triggered. Does anyone have a definitive answer to this? Would be great if you can refer to the official rulings.

I'm thinking about building an Elden Ring proxy deck (after watching this video), and this Atraxa I made would be a fun proxy commander for a poison deck. Do you have any deck recommendations or tips for building a deck that's not too toxic to play against and suitable for casual commander?

Alternatively, a -1/-1 counter deck would also be fun if that's a thing that exists (it doesn't have to be op).