As of yet I cannot see any benefits from having a lot of expensive cards.
The combinations I’ve found that work are those that can deal with thieving cards from opponents (resource generation cycling cards) and quick deployment strategies.
There are few benefits to building up to those 12+ coin cards unless you’re talking about a long game of attrition where those expensive cards will break the balance.
I too play Listrata… By far the most valuable card I’ve found in terms of “nailing it in the coffin” is Benediction (11). I’ve found it far more useful and deadly than Merchant (12) and Bishop (12), and Bishop runs the chance of being stolen by Blue, at which point you’re basically screwed.