It isnt much to go on, but if you see someone with, say, a large amount of Unglued Plains, Mountains, Swamps, and Islands for trade but no Forests, alarm bells should ring in your brain
Find one as low as $235
Its entirely possible to build your decks to prioritize EtB creatures, and if you have access to any ways to flicker your board or recur things from the graveyard, youre suddenly racking up the value
Just remember that Simon's trigger won't care about those cheap instants and sorceries you love to run
Erinis, Gloom Stalker is just the kind of card I love
Of course, that gets stupid with cards like Necropotence or Griselbrand which allow for big life payments, and coupled with a card like Exsanguinate, you can recoup your life loss or even outright win