Elspeth, Suns Champion is particularly well-suited for this, paying you triple on both abilities (each turn!)
The cards are just reminders of the series of triggers each dungeon represents
Per our Grixis Death Shadow example, for Cardhoarder you would set your card value limit to about $415, and for Manatraders you would choose either their Premium plan ($350 card value limit) or their Gold plan ($750 card value limit)
Our sideboard is pretty much a Blood Moon plan with some extra utility cards
Trickster's Elk You want to say Trickster's Elk is like removal, and granted, switching off the busted activated abilities on a key creature is impactful in a singleton format, just make sure you don't care about your opponent controlling a non-flying 3/3 because you might accidentally improve an opposing creature with +1/+1 counters
It's just a shame that it happens to your lands as well