Maybe not individual cards, but concepts/archetypes that I've not seen doing too hot:
Demacia's Elites compared to standard Demacia stuff, especially the early units (Cithria/Battlesmith/Vanguard Defender vs. Fleetfeather Tracker/War Chefs/Brightsteel Protector). I largely blame it on Battlesmith being so easy to remove compared to War Chefs.
Anivia, Tryndamere and, more generally, Freljord Ramp and the expensive Freljord units and spells aside from Hearthguard, Sejuani and the Tuskraider
Ionia's Ephemeral archetype in general
This is great! There are definitely epics tied to these archetypes that aren't providing as much value as they could be. Thanks for the write up
ACarelessWhisperer
This is great! There are definitely epics tied to these archetypes that aren't providing as much value as they could be. Thanks for the write up