OK, so I'm not exactly certain which forum to post this in, so I'll try here.It's not exactly a rules question, but more of a... Desgin question, or strategy question, maybe?
So I played in Silver Gulch for the first time last night, and stumbled across something I couldn't quite grasp the point of. The text on "Sustain The Portal" allows one player to discard a card, allowing you to then discard the top card of the Environment deck. But the damage it does after that isn't preventable, so... Like, why would you bother? I'm assuming there's some interaction here that I'm missing, but I don't see it. Like, I guess if I were playing Haka and wanted to destroy Environment cards, then sure. But otherwise, I kinda... Don't get it?
It works with Lost in the Past (thanks grysqrl). If that card is out, and there are no cards in the trash, you lose. Since it is actually really hard for the trash to run out, there isn’t much of a point to discard a card.
Also, Haka only draws a card when they are destroyed not discarded.
Lost in the Past causes you to lose if there are no cards in the environment trash. This gives you another way to get a card into that trash. It is also useful if you know something nasty is on top of the environment deck and want to get rid of it.
Edit: I guess you could use also use it to accelerate an Akash'Bhuta flip. So, there are a few very specific cases where this is useful, but most of the time people probably don't discard for it.