I have some google play credit, and was wondering what the best investment is here. I don't have any of the solo adventures and only really have cards from classic. Should I arena, get adventures or just packs?

Solo adventures imo if you already have the good classic cards.

What cards from classic are necessity?

Cards that you want to have no matter what deck you're playing are cards like Sylvannas, Harrison Jones, Ragnaros, Thalnos, and some of the other top legendaries. They usually end up being in a few top decks every expansion. Outside of the neutral legendaries it starts to depend on what decks you like to play.

So should i focus on getting those before anything else? I have sylvanas and thalnos not the other 2. If so what's the best way to go about that?

Thank you so much for your help

This post was edited by Takoyaki on Nov 3 2016 07:40am

I would still get the adventures first, but then spend gold on classic packs. Arena is a bad idea imo.

Is there a better adventure? Are some standard and some not? Sorry this is noobish

http://hearthstone.gamepedia.com/Standard_format

Blackrock Mountain - League of Explorers - Karazhan all are currently in standard. Blackrock and League of Explorers will rotate out (I think, it's at least Blackrock) when the new season starts. Blackrock has some awesome cards but if your resources are limited I would shoot for Karazhan since it's going to be around for a while. I recommend you purchase at minimum 1 wing of the others though so that you can pursue the other wings down the road if you want to unlock them.