The reason I put Beneath the Grounds in the deck was to counter Reno decks, so they could not pull off their combos. This works even better when combined with cards like Mimic Pod and Valeera the Hollow to allow you to block their combos for the entire game, but I understand your confusion. If you really want to switch it out, Tar Creeper is a good replacement.
No conceal, Cold blood, Sherazin, Swashburglar or SI:7 Agent? Beneath the grounds is trash so why run it?
The reason I put Beneath the Grounds in the deck was to counter Reno decks, so they could not pull off their combos. This works even better when combined with cards like Mimic Pod and Valeera the Hollow to allow you to block their combos for the entire game, but I understand your confusion. If you really want to switch it out, Tar Creeper is a good replacement.