Karn, Silver Golem, Masticore, Memory Jar, and Mox Diamond in From the Vault: Relics
Sealed Product Availability A good store should carry: ETBs Booster Boxes Collection Boxes Graded Cards Many collectors enjoy browsing professionally graded inventory
Later down the line as Pokemon TCG Pocket introduces new packs to open, it may be worth saving your Pack Hourglasses for these if your current collections are near complete
As I already mentioned playing the events is the best way of farming cards for your collection and with the normal draft mode and sealed events, the game gives you good options of getting several booster packs and getting more than the paid value in a run if you reach the 50% win rate mark
Starting with Scrappy Survivors, this is a WRG deck headed up by Dogmeat, Ever Loyal
Formats like Modern that run a lot of fetch lands can make even better use of this card as you can find it more easily