Any two-mana counterspell with only one Blue pip in its casting cost gets a big boost in my view, so Im pretty fond of Negate and its variants
Interaction I put a precious Shadowspear in here for the lifegain and the ability to punch damage through by giving a large Relentless Rats trample, and its ability to turn off hexproof and indestructible for my opponents is always clutch
Even with purchasing through a vendor, there's an element of risk involved in buying damaged cards
The world design was beautiful, the characters were interesting, and they introduced a ton of mechanics that were really fun, even if some were pretty hit-or-miss
Instead, it is influenced by a combination of rarity, condition, demand, and historical significance