As the franchise has developed, rare chase cards and valuable hits have become harder to pull, with in-demand cards like the Eevee Heroes being notably difficult to find
Tax Collector is the most likely to see any play
It could be an excellent blue commander for a storm deck or just general spellslinger value by discounting cards like Nexus of Fate and Mnemonic Deluge
I will keep an eye on the longshot Dragon, but more traditional win conditions are coming down the pike
Beyond that there is how immediate the life gain is, how much you get or can potentially get, how cheap the card or effect is and how hard it is to disrupt
Dark types resist 2 types, which they receive half damage from: Dark - Theyre aware of the underhanded tactics their own type uses, and are unlikely to fall for them