Its drawback may look like its very punishing and can allow the opponent to surprise you via a mid-combat spell, but I never really saw that scenario play out since its damage prevention ability is a a conditional static ability so as long as its on when damage is dealt, it wont be prevented. (Thank you, @fenaris!) It usually plays out somewhat like a colorless Ashenmoor Gouger / Chimeric Idol where you typically dont bother trying to block with it (why am I blocking with my aggro guys anyway?) and, if need be, you cast a spell pre-combat to activate it (typically I used a large coin, like a quarter, to denote whether it was on or off)
So with that, we ended up with our four game selects
They arent the most efficient cards, and I dont like the double color pips on two of them in a five-color deck, but the flavor is on point
The more desirable Masterpiece cards such as Sol Ring and Mana Crypt will always hold a significant premium over the less desirable ones
Based on the latest market prices tracked on TCG Stacked, The Fire Crystal is worth about $10.12 USD for a regular copy and $11.35 USD for a foil copy