For MTG proxies, you want at least blue/black core board, around 300 gsm and 0.3 mm, plus decent printing and cutting, to get close to real MTG cards in sleeves
Each Sliver creature card in your graveyard has Encore X, where X is its mana value
Heck, the only card that doesn't SS is Tour Bus, which is still decent here for the recycling shenanigans that come with it and Fortune Tune
Many, like me, are fair weather TCG players who have one deck that they sporadically update and play a couple of games with, but otherwise just collect cool cards that speak to them
Starfoil Rare (SFR): Starfoil Rare cards are similar to Parallel Rare cards and were introduced to TCG with Battle Pack: Epic Dawn
There are 15 available to collect in total, most of them themed around dragon Pokmon like Hydreigon and Dragonite