where do Tradable packs come from?

So noob question but where do tradable/inventory packs come from? Specifically like xp, auto loot & auto gold pick up packs are the once I'm interested in, are they bought with plat from somewhere or are they farmed?

u can get em during events

They can be obtained from opening crates or farming during certain events.

When you have untradeable and tradeable versions of the same pack, it always opens the untradeable ones first no matter which you click. It's a bug

Kodi nox